Patent Publication Number: US-2023160787-A1

Title: Filtration sampling devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of International Application PCT/IL2022/050024, filed Jan. 6, 2022, which published as WO 2022/149135 to Feldman et al., and which claims priority from U.S. Provisional Application 63/134,282, filed Jan. 6, 2021. 
     The present application is related to a U.S. application filed on even date herewith, entitled, “Filtration Sampling Devices,” which is a continuation of International Application PCT/IL2022/050024, filed Jan. 6, 2022, which claims priority from U.S. Provisional Application 63/134,282, filed Jan. 6, 2021. 
     All of the above-referenced applications are assigned to the assignee of the present application and incorporated herein by reference. 
    
    
     FIELD OF THE APPLICATION 
     Applications of the present invention relate to sampling biological liquids. 
     BACKGROUND OF THE APPLICATION 
     Many techniques exist for testing for the presence of bacteria and viruses for aiding in disease diagnosis. For example, testing for the Influenza virus includes molecular-based detection methods, viral culture methods, and immunoassay methods. Influenza virus testing includes the testing of nasal swabs, nasopharyngeal swabs, nasal aspirates, nasopharyngeal aspirates, nasal washes, nasopharyngeal washes, throat swabs, and a combination of samples. 
     PCT Publication WO 2018/158768 to Fruchter et al. describes inter alia a method for testing for presence of a particulate selected from the group consisting of: a microorganism, a fungus, a bacteria, a spore, a virus, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen. The method includes (a) collecting, in a tube, fluid that potentially contains the particulate, (b) using a plunger to push the fluid through a filter disposed at a distal portion of the tube or at a distal end of the plunger, and subsequently, (c) while the filter is inside the tube, ascertaining if any of the particulate was trapped by the filter by applying a particulate-presence-testing-facilitation solution to the filter. 
     PCT Publication WO 2020/049569 to Fruchter et al. describes inter alia a testing device for testing for the presence of particulate in a liquid. The testing device includes a liquid container for containing the liquid; a filter, disposed in or downstream of the liquid container; a liquid-pressure source, which is arranged to apply pressure to drive the liquid contained in the liquid container through the filter; and a filter chamber that is (a) disposed downstream of the liquid container, (b) shaped so as to define an inlet, and (c) in fluid communication with the filter. 
     US Patent Application Publication 2011/0318814 to Kshirsagar et al. describes inter alia a method for isolating microorganisms from a sample, the sample including sample matrix and microorganisms, the method including the steps of providing a receptacle, the receptacle configured to allow filtering of the sample and to reversibly contain the sample and a concentration agent; adding the sample to the receptacle, wherein a microorganism-bound composition will be formed in the receptacle, the microorganism-bound composition including concentration agent-bound microorganisms and sample matrix; and filtering the microorganism-bound composition through a filter to collect the concentration agent-bound microorganisms on the filter. The filter has an average pore size that is greater than the average size of the microorganisms. Kits and systems are also described. 
     SUMMARY OF THE APPLICATION 
     Some applications of the present invention provide sampling devices for concentrating a liquid specimen sample. Some of the sampling devices comprise a filtration assembly and a collection vial disengageably coupled to the filtration assembly. The filtration assembly comprises a tubular container for receiving the liquid specimen sample, a plunger, and a filter disposed in the tubular container. The filtration assembly is configured such that movement of a plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter. 
     The sampling device is configured such that the filter is advanceable into the collection vial via a vial opening while the collection vial is disengageably coupled to the filtration assembly. Once the collection vial has been disengaged from the filtration assembly, a diagnostic test may be performed for the presence of particulate trapped by the filter, which is now in the collection vial. For some applications, such as for transporting the collection vial to a remote diagnostic laboratory, the sampling device further comprises a collection vial cap, which is configured to seal the vial opening. 
     Some of the sampling devices do not necessarily comprise a collection vial. The plunger of these sampling devices comprises a plunger head and a plunger rod. The plunger rod has a distal end portion to which the plunger head is coupled, and is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod. These sampling devices are configured such that the filter is removable from the tubular container via the plunger-space proximal opening while the plunger head is within the tubular container. 
     In some configurations, the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space. The sampling device comprises a filter-withdrawal shaft, which includes a distal portion that is directly or indirectly coupled to the filter, and which is disposed passing through the internal plunger space. The sampling device is configured such that proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls the filter into the internal plunger space via the plunger-head opening and out of the internal plunger space via the plunger-space proximal opening, and removes the filter-withdrawal shaft and the filter from the filtration assembly. 
     There is therefore provided, in accordance with an Inventive Concept 1 of the present invention, a sampling device for concentrating a liquid specimen sample, the sampling device comprising: 
     a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define an inner wall and a proximal container opening for receiving the liquid specimen sample;   (ii) a plunger, which (A) comprises a plunger head and a plunger rod, which (1) has a distal end portion to which the plunger head is coupled, and (2) is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall; and   (iii) a filter,       

     wherein the filtration assembly is configured such that movement of the plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter, and 
     wherein the sampling device is configured such that the filter is removable from the tubular container via the plunger-space proximal opening while the plunger head is within the tubular container. 
     Inventive Concept 2. The sampling device according to Inventive Concept 1, 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) includes a distal portion that is directly or indirectly coupled to the filter, and (b) which is disposed passing through the internal plunger space, and 
     wherein the sampling device is configured such that proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls the filter into the internal plunger space via the plunger-head opening and out of the internal plunger space via the plunger-space proximal opening, and removes the filter-withdrawal shaft and the filter from the filtration assembly. 
     Inventive Concept 3. The sampling device according to Inventive Concept 2, 
     wherein the sampling device comprises a filter receptacle that is slidably coupled to a distal end portion of the filter-withdrawal shaft and shaped so as to define a distal receptacle opening, and 
     wherein the sampling device is configured such that the proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls a portion of the filter into the filter receptacle via the distal receptacle opening. 
     Inventive Concept 4. The sampling device according to Inventive Concept 2, further comprising an extraction-tube cap, which (a) is disposed radially surrounding the filter-withdrawal shaft along a first longitudinal portion of the filter-withdrawal shaft, such that a distal second longitudinal portion of the filter-withdrawal shaft is distal to the extraction-tube cap, and (b) has an outer diameter that is greater than an outer diameter of the filter-withdrawal shaft.
 
Inventive Concept 5. The sampling device according to Inventive Concept 4, further comprising an extraction tube having a proximal end opening, wherein the filter-withdrawal shaft, the filter, the extraction tube, and the extraction-tube cap are configured such that the filter and the distal second longitudinal portion of the filter-withdrawal shaft are disposable within the extraction tube via the proximal end opening of the extraction tube, such that the extraction-tube cap seals at least a portion of the extraction tube.
 
Inventive Concept 6. The sampling device according to Inventive Concept 4, wherein the filter-withdrawal shaft is shaped so as to define, proximal to the extraction-tube cap, a proximal third longitudinal portion that is configured to provide a predetermined separation border between the proximal third longitudinal portion and the filter-withdrawal shaft distal to the predetermined separation border.
 
Inventive Concept 7. The sampling device according to Inventive Concept 6, wherein the proximal third longitudinal portion is directly longitudinally adjacent the extraction-tube cap.
 
Inventive Concept 8. The sampling device according to Inventive Concept 6, wherein the proximal third longitudinal portion is longitudinally connected to the first longitudinal portion of the filter-withdrawal shaft by a fourth longitudinal portion of the filter-withdrawal shaft longitudinally between the predetermined separation border and the extraction-tube cap.
 
Inventive Concept 9. The sampling device according to Inventive Concept 6, wherein the predetermined separation border is defined by a lesser cross-sectional area of the filter-withdrawal shaft at the predetermined separation border than longitudinally adjacent to the predetermined separation border.
 
Inventive Concept 10. The sampling device according to Inventive Concept 6, wherein the predetermined separation border is defined by scoring.
 
Inventive Concept 11. The sampling device according to Inventive Concept 6, wherein the predetermined separation border is defined by perforation.
 
Inventive Concept 12. The sampling device according to Inventive Concept 6, wherein the predetermined separation border is defined by corresponding male and female screw threads.
 
Inventive Concept 13. The sampling device according to Inventive Concept 6, wherein the predetermined separation border is defined by corresponding male and female tapered friction-fitting surfaces.
 
Inventive Concept 14. The sampling device according to Inventive Concept 6, wherein the filter-withdrawal shaft is shaped so as to define an internal channel that passes longitudinally through the first longitudinal portion and has (a) one or more distal openings distal to the extraction-tube cap and (b) a proximal opening that is disposed at the predetermined separation border and that is open to outside the filter-withdrawal shaft upon separation of the proximal third longitudinal portion at the predetermined separation border.
 
Inventive Concept 15. The sampling device according to Inventive Concept 14, further comprising an extraction tube having a proximal end opening, wherein the filter-withdrawal shaft, the filter, the extraction tube, and the extraction-tube cap are configured such that the filter and the distal second longitudinal portion of the filter-withdrawal shaft are disposable within the extraction tube via the proximal end opening of the extraction tube, such that the extraction-tube cap seals at least a portion of the extraction tube other than allowing fluid flow through the internal channel via the one or more distal openings and the proximal opening.
 
Inventive Concept 16. The sampling device according to Inventive Concept 2,
 
     wherein the plunger rod is shaped so as to define therewithin a waste liquid receptacle, 
     wherein the plunger head is shaped so as to define a filter support, which is shaped so as to define (a) a distal support surface, (b) a plurality of filtrate-passage openings through the filter support into the waste liquid receptacle, and (c) the plunger-head opening, 
     wherein the filter is disposed on the distal support surface, and 
     wherein the filtration assembly is configured such that movement of the plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter and the filtrate-passage openings and into the waste liquid receptacle. 
     Inventive Concept 17. The sampling device according to Inventive Concept 2, 
     wherein the plunger-space proximal opening and a longitudinal portion of the filter-withdrawal shaft are shaped so as to define corresponding female and male screw threads, respectively, which (a) removably couple the filter-withdrawal shaft to the plunger rod while the filter-withdrawal shaft is disposed passing through the internal plunger space, and (b) prevent the premature proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, and 
     wherein the sampling device is configured such that rotation of the filter-withdrawal shaft and the plunger-space proximal opening with respect to each other (a) causes an initial portion of the proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, and (b) decouples the female and the male screw threads from each other. 
     Inventive Concept 18. The sampling device according to Inventive Concept 1, 
     wherein the sampling device further comprises a collection vial, which is disengageably coupled to the filtration assembly, and 
     wherein the sampling device is configured such that the filter is advanceable into the collection vial while the collection vial is disengageably coupled to the filtration assembly. 
     Inventive Concept 19. The sampling device according to Inventive Concept 18, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 20. The sampling device according to Inventive Concept 18, wherein the collection vial is removably disposed at least partially within the internal plunger space.
 
Inventive Concept 21. The sampling device according to Inventive Concept 20, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 22. The sampling device according to Inventive Concept 20,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is shaped so as to define a vial opening and a shaft-passage hole at an end of the collection vial opposite the vial opening, 
     wherein the sampling device is configured such that the filter is advanceable into the collection vial via the plunger-head opening and the vial opening while the collection vial is disengageably coupled to the filtration assembly, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) is disposed partially within the collection vial within the internal plunger space, (b) includes a proximal portion that is slidably disposed passing through the shaft-passage hole, and (c) includes a distal portion that passes through the vial opening and is directly or indirectly coupled to the filter, and 
     wherein the sampling device is configured such that proximal withdrawal of the filter-withdrawal shaft, while the plunger head is within the tubular container, pulls the filter into the collection vial via the plunger-head opening and the vial opening. 
     Inventive Concept 23. The sampling device according to Inventive Concept 22, wherein the sampling device is configured such that further proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls the collection vial out of the internal plunger space via the plunger-space proximal opening.
 
Inventive Concept 24. The sampling device according to Inventive Concept 22, further comprising a seal that inhibits fluid leakage between the proximal portion of the filter-withdrawal shaft and the shaft-passage hole.
 
Inventive Concept 25. The sampling device according to Inventive Concept 20, wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, and wherein the collection vial is elongatable from the axially-compressed configuration.
 
Inventive Concept 26. The sampling device according to Inventive Concept 25, wherein a wall of the collection vial is accordion-shaped.
 
Inventive Concept 27. The sampling device according to Inventive Concept 20, wherein the collection vial comprises a flexible material and is removably disposed at least partially within the internal plunger space while the collection vial is an inverted configuration, in which the inverted collection vial defines a proximal vial opening.
 
Inventive Concept 28. The sampling device according to Inventive Concept 27, wherein the inverted configuration is a double-inverted configuration.
 
Inventive Concept 29. The sampling device according to Inventive Concept 27,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) is disposed partially within the inverted collection vial within the internal plunger space, and (b) includes a distal portion that is directly or indirectly coupled to the filter, 
     wherein the sampling device is configured such that proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, inverts the inverted collection vial to an uninverted configuration, pulls the filter into the collection vial via the plunger-head opening, pulls the collection vial out of the internal plunger space via the plunger-space proximal opening, and removes the filter-withdrawal shaft and the filter from the filtration assembly. 
     Inventive Concept 30. The sampling device according to Inventive Concept 18, wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly.
 
Inventive Concept 31. The sampling device according to Inventive Concept 30,
 
     wherein the sampling device further comprises a shaft, and 
     wherein the sampling device is configured such that that a distal portion of the shaft is axially movable through the vial opening so as to advance the filter into the collection vial via the vial opening. 
     Inventive Concept 32. The sampling device according to Inventive Concept 31, 
     wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, 
     wherein the collection vial is elongatable from the axially-compressed configuration, and 
     wherein the sampling device is configured such that proximal withdrawal of the shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls the filter into the collection vial and elongates the collection vial. 
     Inventive Concept 33. The sampling device according to Inventive Concept 30, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 34. The sampling device according to Inventive Concept 33, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly without any proximal withdrawal of the plunger head within the tubular container.
 
Inventive Concept 35. The sampling device according to Inventive Concept 18, wherein the sampling device is configured such that the filter is advanceable into the collection vial while the plunger head is within the tubular container.
 
Inventive Concept 36. The sampling device according to Inventive Concept 35, wherein the sampling device is configured such that the filter is advanceable into the collection vial while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 37. The sampling device according to Inventive Concept 18, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly by distal movement of the collection vial with respect to the tubular container.
 
Inventive Concept 38. The sampling device according to Inventive Concept 18,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is positioned proximal to the plunger head, and 
     wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening. 
     Inventive Concept 39. The sampling device according to Inventive Concept 38, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 40. The sampling device according to Inventive Concept 38,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 41. The sampling device according to Inventive Concept 38, 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the sampling device further comprises a fluid-tight frangible seal, and wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 42. A testing kit comprising the sampling device according to any one of Inventive Concepts 1-41, the testing kit further comprising a lateral flow immunoassay test strip, which is configured to detect the presence of a biological particulate trapped by the filter.
 
Inventive Concept 43. The testing kit according to Inventive Concept 42, further comprising reagents for use with the lateral flow immunoassay test strip.
 
Inventive Concept 44. The testing kit according to Inventive Concept 42, wherein the biological particulate is selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen.
 
     There is further provided, in accordance with an Inventive Concept 45 of the present invention, a method for concentrating a liquid specimen sample, the method comprising: 
     placing the liquid specimen sample in a tubular container of a filtration assembly of a sampling device; 
     inserting a plunger head of a plunger of the filtration assembly into the tubular container via a proximal container opening of the tubular container, such that a lateral surface of the plunger head forms a fluid-tight movable seal with an inner wall of the tubular container, wherein the plunger includes a plunger rod that (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod; 
     distally advancing the plunger head within the tubular container to drive at least a portion of the liquid specimen sample through a filter disposed in the tubular container; and 
     removing the filter from the tubular container via the plunger-space proximal opening while the plunger head is within the tubular container. 
     Inventive Concept 46. The method according to Inventive Concept 45, 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the sampling device includes a filter-withdrawal shaft, which (a) includes a distal portion that is directly or indirectly coupled to the filter, and (b) is disposed passing through the internal plunger space, and 
     wherein removing the filter from the tubular container comprises proximally withdrawing the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, so as to pull the filter into the internal plunger space via the plunger-head opening and out of the internal plunger space via the plunger-space proximal opening, and to remove the filter-withdrawal shaft and the filter from the filtration assembly. 
     Inventive Concept 47. The method according to Inventive Concept 46, 
     wherein the sampling device includes a filter receptacle that is slidably coupled to a distal end portion of the filter-withdrawal shaft and shaped so as to define a distal receptacle opening, and 
     wherein proximally withdrawing the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls a portion of the filter into the filter receptacle via the distal receptacle opening. 
     Inventive Concept 48. The method according to Inventive Concept 46, wherein the sampling device further comprises an extraction-tube cap, which (a) is disposed radially surrounding the filter-withdrawal shaft along a first longitudinal portion of the filter-withdrawal shaft, such that a distal second longitudinal portion of the filter-withdrawal shaft is distal to the extraction-tube cap, and (b) has an outer diameter that is greater than an outer diameter of the filter-withdrawal shaft.
 
Inventive Concept 49. The method according to Inventive Concept 48, further comprising disposing the filter and the distal second longitudinal portion of the filter-withdrawal shaft are disposable within the extraction tube via a proximal end opening of the extraction tube, such that the extraction-tube cap seals at least a portion of the extraction tube.
 
Inventive Concept 50. The method according to Inventive Concept 48,
 
     wherein the filter-withdrawal shaft is shaped so as to define, proximal to the extraction-tube cap, a proximal third longitudinal portion that is configured to provide a predetermined separation border between the proximal third longitudinal portion and the filter-withdrawal shaft distal to the predetermined separation border, and 
     wherein the method further comprises separating, at the predetermined separation border, the proximal third longitudinal portion from the filter-withdrawal shaft distal to the predetermined separation border. 
     Inventive Concept 51. The method according to Inventive Concept 50, wherein the proximal third longitudinal portion is directly longitudinally adjacent the extraction-tube cap.
 
Inventive Concept 52. The method according to Inventive Concept 50, wherein the proximal third longitudinal portion is longitudinally connected to the first longitudinal portion of the filter-withdrawal shaft by a fourth longitudinal portion of the filter-withdrawal shaft longitudinally between the predetermined separation border and the extraction-tube cap.
 
Inventive Concept 53. The method according to Inventive Concept 50, wherein the predetermined separation border is defined by a lesser cross-sectional area of the filter-withdrawal shaft at the predetermined separation border than longitudinally adjacent to the predetermined separation border, and wherein separating comprises breaking the filter-withdrawal shaft at the predetermined separation border.
 
Inventive Concept 54. The method according to Inventive Concept 50, wherein the predetermined separation border is defined by scoring, and wherein separating comprises breaking the filter-withdrawal shaft at the predetermined separation border.
 
Inventive Concept 55. The method according to Inventive Concept 50, wherein the predetermined separation border is defined by perforation, and wherein separating comprises breaking the filter-withdrawal shaft at the predetermined separation border.
 
Inventive Concept 56. The method according to Inventive Concept 50, wherein the predetermined separation border is defined by corresponding male and female screw threads, and wherein separating comprises unscrewing the male and the female screw threads from each other.
 
Inventive Concept 57. The method according to Inventive Concept 50, wherein the predetermined separation border is defined by corresponding male and female tapered friction-fitting surfaces, and wherein separating comprises separating the male and the female tapered friction-fitting surfaces from each other.
 
Inventive Concept 58. The method according to Inventive Concept 50,
 
     wherein the filter-withdrawal shaft is shaped so as to define an internal channel that passes longitudinally through the first longitudinal portion and has (a) one or more distal openings distal to the extraction-tube cap and (b) a proximal opening that is disposed at the predetermined separation border and that is open to outside the filter-withdrawal shaft upon separation of the proximal third longitudinal portion at the predetermined separation border, and 
     wherein the method further comprises dripping a liquid through the internal channel and out of the proximal opening. 
     Inventive Concept 59. The method according to Inventive Concept 58, further comprising disposing the filter and the distal second longitudinal portion of the filter-withdrawal shaft are disposable within the extraction tube via a proximal end opening of the extraction tube, such that the extraction-tube cap seals at least a portion of the extraction tube other than allowing fluid flow through the internal channel via the one or more distal openings and the proximal opening.
 
Inventive Concept 60. The method according to Inventive Concept 46,
 
     wherein the plunger rod is shaped so as to define therewithin a waste liquid receptacle, 
     wherein the plunger head is shaped so as to define a filter support, which is shaped so as to define (a) a distal support surface, (b) a plurality of filtrate-passage openings through the filter support into the waste liquid receptacle, and (c) the plunger-head opening, 
     wherein the filter is disposed on the distal support surface, and 
     wherein distally advancing the plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter and the filtrate-passage openings and into the waste liquid receptacle. 
     Inventive Concept 61. The method according to Inventive Concept 46, 
     wherein the plunger-space proximal opening and a longitudinal portion of the filter-withdrawal shaft are shaped so as to define corresponding female and male screw threads, respectively, which (a) removably couple the filter-withdrawal shaft to the plunger rod while the filter-withdrawal shaft is disposed passing through the internal plunger space, and (b) prevent the premature proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, and 
     wherein proximally withdrawing the filter-withdrawal shaft out of the internal plunger space comprises rotating the filter-withdrawal shaft and the plunger-space proximal opening with respect to each other so as to (a) cause an initial portion of the proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, and (b) decouple the female and the male screw threads from each other. 
     Inventive Concept 62. The method according to Inventive Concept 45, 
     wherein the sampling device further includes a collection vial, which is disengageably coupled to the filtration assembly, and 
     wherein the method further comprises advancing the filter into the collection vial while the collection vial is disengageably coupled to the filtration assembly. 
     Inventive Concept 63. The method according to Inventive Concept 62, further comprising decoupling the collection vial from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 64. The method according to Inventive Concept 62, wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head within the tubular container while the collection vial is removably disposed at least partially within the internal plunger space.
 
Inventive Concept 65. The method according to Inventive Concept 64, wherein decoupling the collection vial from the filtration assembly comprises decoupling the collection vial from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 66. The method according to Inventive Concept 64,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is shaped so as to define a vial opening and a shaft-passage hole at an end of the collection vial opposite the vial opening, 
     wherein the sampling device includes a filter-withdrawal shaft, which (a) is disposed partially within the collection vial within the internal plunger space, (b) includes a proximal portion that is slidably disposed passing through the shaft-passage hole, and (c) includes a distal portion that passes through the vial opening and is directly or indirectly coupled to the filter, and 
     wherein advancing the filter into the collection vial comprises proximally withdrawing the filter-withdrawal shaft, while the plunger head is within the tubular container, so as to pull the filter into the collection vial via the plunger-head opening and the vial opening, while the collection vial is disengageably coupled to the filtration assembly. 
     Inventive Concept 67. The method according to Inventive Concept 66, wherein decoupling the collection vial from the filtration assembly comprises further proximally withdrawing the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, so as to pull the collection vial out of the internal plunger space via the plunger-space proximal opening.
 
Inventive Concept 68. The method according to Inventive Concept 64,
 
     wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, and 
     wherein the method further comprises elongating the collection vial from the axially-compressed configuration. 
     Inventive Concept 69. The method according to Inventive Concept 68, wherein a wall of the collection vial is accordion-shaped.
 
Inventive Concept 70. The method according to Inventive Concept 64, wherein the collection vial includes a flexible material and is removably disposed at least partially within the internal plunger space while the collection vial is an inverted configuration, in which the inverted collection vial defines a proximal vial opening.
 
Inventive Concept 71. The method according to Inventive Concept 70, wherein the inverted configuration is a double-inverted configuration.
 
Inventive Concept 72. The method according to Inventive Concept 70,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the sampling device includes a filter-withdrawal shaft, which (a) is disposed partially within the inverted collection vial within the internal plunger space, and (b) includes a distal portion that is directly or indirectly coupled to the filter, and 
     wherein removing the filter from the tubular container comprises proximally withdrawing the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, so as to invert the inverted collection vial to an uninverted configuration, to pull the filter into the collection vial via the plunger-head opening, to pull the collection vial out of the internal plunger space via the plunger-space proximal opening, and to remove the filter-withdrawal shaft and the filter from the filtration assembly. 
     Inventive Concept 73. The method according to Inventive Concept 62, wherein the collection vial is shaped so as to define a vial opening, and wherein the method further comprising advancing the filter into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly.
 
Inventive Concept 74. The method according to Inventive Concept 73,
 
     wherein the sampling device further includes a shaft, and 
     wherein advancing the filter into the collection vial comprises axially moving a distal portion of the shaft through the vial opening. 
     Inventive Concept 75. The method according to Inventive Concept 74, 
     wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, 
     wherein the collection vial is elongatable from the axially-compressed configuration, and 
     wherein advancing the filter into the collection vial comprises proximally withdrawing the shaft out of the internal plunger space, while the plunger head is within the tubular container, so as to pull the filter into the collection vial and to elongate the collection vial. 
     Inventive Concept 76. The method according to Inventive Concept 73, wherein decoupling the collection vial from the filtration assembly comprises decoupling the collection vial from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 77. The method according to Inventive Concept 76, wherein decoupling the collection vial from the filtration assembly comprises decoupling the collection vial from the filtration assembly without proximally withdrawing the plunger head within the tubular container.
 
Inventive Concept 78. The method according to Inventive Concept 62, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial while the plunger head is within the tubular container.
 
Inventive Concept 79. The method according to Inventive Concept 78, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 80. The method according to Inventive Concept 62, wherein decoupling the collection vial from the filtration assembly comprises distally moving the collection vial with respect to the tubular container.
 
Inventive Concept 81. The method according to Inventive Concept 62,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is positioned proximal to the plunger head, and 
     wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head and the collection vial within the tubular container so as to advance the filter into the collection vial via the plunger-head opening. 
     Inventive Concept 82. The method according to Inventive Concept 81, wherein distally advancing the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 83. The method according to Inventive Concept 81,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 84. The method according to Inventive Concept 81, 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the sampling device further includes a fluid-tight frangible seal, wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 85. The method according to Inventive Concept 62, 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is positioned proximal to the plunger head, and 
     wherein advancing the filter into the collection vial comprises moving the plunger head and the collection vial within the tubular container so as to advance the filter into the collection vial via the plunger-head opening. 
     Inventive Concept 86. The method according to Inventive Concept 85, wherein moving the plunger head and the collection vial within the tubular container comprises moving the plunger head and the collection vial within the tubular container so as to advance the filter into the collection vial via the plunger-head opening while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 87. The method according to Inventive Concept 85,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 88. The method according to Inventive Concept 85, 
     wherein the collection vial is shaped so as to define a vial opening, and wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the sampling device further comprises a fluid-tight frangible seal, wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 89. The method according to any one of Inventive Concepts 45-88, further comprising, after the filter has been removed from the tubular container, detecting the presence of a biological particulate trapped by the filter.
 
Inventive Concept 90. The method according to Inventive Concept 89, wherein detecting the presence of the biological particulate trapped by the filter comprising using a lateral flow immunoassay test strip to detect the presence of the biological particulate trapped by the filter.
 
Inventive Concept 91. The method according to Inventive Concept 89, wherein the biological particulate is selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen.
 
     There is still further provided, in accordance with an Inventive Concept 92 of the present invention, a sampling device for concentrating a liquid specimen sample, the sampling device comprising: 
     (a) a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define an inner wall and a proximal container opening for receiving the liquid specimen sample;   (ii) a plunger, which (A) comprises a plunger head, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall; and   (iii) a filter; and       

     (b) a collection vial, which is disengageably coupled to the filtration assembly, 
     wherein the filtration assembly is configured such that movement of the plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter, and 
     wherein the sampling device is configured such that the filter is advanceable into the collection vial while the collection vial is disengageably coupled to the filtration assembly. 
     Inventive Concept 93. The sampling device according to Inventive Concept 92, wherein the sampling device is configured such that the filter is advanceable entirely into the collection vial while the collection vial is disengageably coupled to the filtration assembly.
 
Inventive Concept 94. The sampling device according to Inventive Concept 92, wherein the collection vial is disengageably coupled to the tubular container of the filtration assembly.
 
Inventive Concept 95. The sampling device according to Inventive Concept 92, wherein the collection vial is not shaped so as to define any pressure-release openings and does not comprise any pressure-release valves.
 
Inventive Concept 96. The sampling device according to Inventive Concept 92, wherein the collection vial has a volume of between 1 and 50 ml.
 
Inventive Concept 97. The sampling device according to Inventive Concept 92,
 
     wherein the plunger comprises a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod, and 
     wherein the sampling device is configured such that the collection vial is removable from the filtration assembly via the plunger-space proximal opening while the plunger head is within the tubular container. 
     Inventive Concept 98. The sampling device according to Inventive Concept 97, 
     wherein the plunger rod is shaped so as to define therewithin a waste liquid receptacle, 
     wherein the plunger head is shaped so as to define a filter support, which is shaped so as to define (a) a distal support surface, (b) a plurality of filtrate-passage openings through the filter support into the waste liquid receptacle, and (c) the plunger-head opening, 
     wherein the filter is disposed on the distal support surface, and 
     wherein the filtration assembly is configured such that movement of the plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter and the filtrate-passage openings and into the waste liquid receptacle. 
     Inventive Concept 99. The sampling device according to Inventive Concept 97, wherein the collection vial is removably disposed at least partially within the internal plunger space.
 
Inventive Concept 100. The sampling device according to Inventive Concept 99,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is shaped so as to define a vial opening and a shaft-passage hole at an end of the collection vial opposite the vial opening, 
     wherein the sampling device is configured such that the filter is advanceable into the collection vial via the plunger-head opening and the vial opening while the collection vial is disengageably coupled to the filtration assembly, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) is disposed partially within the collection vial within the internal plunger space, (b) includes a proximal portion that is slidably disposed passing through the shaft-passage hole, and (c) includes a distal portion that is directly or indirectly coupled to the filter, and 
     wherein the sampling device is configured such that proximal withdrawal of the filter-withdrawal shaft, while the plunger head is within the tubular container, pulls the filter into the collection vial via the plunger-head opening and the vial opening. 
     Inventive Concept 101. The sampling device according to Inventive Concept 99, wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, and wherein the collection vial is elongatable from the axially-compressed configuration.
 
Inventive Concept 102. The sampling device according to Inventive Concept 101, wherein a wall of the collection vial is accordion-shaped.
 
Inventive Concept 103. The sampling device according to Inventive Concept 99, wherein the collection vial comprises a flexible material and is removably disposed at least partially within the internal plunger space while the collection vial is an inverted configuration, in which the inverted collection vial defines a proximal vial opening.
 
Inventive Concept 104. The sampling device according to Inventive Concept 103, wherein the inverted configuration is a double-inverted configuration.
 
Inventive Concept 105. The sampling device according to Inventive Concept 103,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) is disposed partially within the inverted collection vial within the internal plunger space, and (b) includes a distal portion that is directly or indirectly coupled to the filter, 
     wherein the sampling device is configured such that proximal withdrawal of the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, inverts the inverted collection vial to an uninverted configuration, pulls the filter into the collection vial via the plunger-head opening, pulls the collection vial out of the internal plunger space via the plunger-space proximal opening, and removes the filter-withdrawal shaft and the filter from the filtration assembly. 
     Inventive Concept 106. The sampling device according to Inventive Concept 92, wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly.
 
Inventive Concept 107. The sampling device according to any one of Inventive Concepts 92-106, wherein the sampling device is configured such that the filter is advanceable into the collection vial while the plunger head is within the tubular container.
 
Inventive Concept 108. The sampling device according to Inventive Concept 107, wherein the sampling device is configured such that the filter is advanceable into the collection vial while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 109. The sampling device according to Inventive Concept 107, wherein the sampling device is configured such that the filter is advanceable into the collection vial without any proximal withdrawal of the plunger head within the tubular container.
 
Inventive Concept 110. The sampling device according to any one of Inventive Concepts 92-106, wherein the filtration assembly is configured such that when the plunger head is within the tubular container, fluid communication is blocked between (a) the tubular container distal to the plunger head and (b) the proximal container opening.
 
Inventive Concept 111. The sampling device according to Inventive Concept 110, wherein the filter is advanceable into the collection vial while the plunger head is within the tubular container.
 
Inventive Concept 112. The sampling device according to any one of Inventive Concepts 92-96,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, 
     wherein the sampling device further comprises a shaft, and 
     wherein the sampling device is configured such that that a distal portion of the shaft is axially movable through the vial opening so as to advance the filter into the collection vial via the vial opening. 
     Inventive Concept 113. The sampling device according to Inventive Concept 112, 
     wherein the plunger comprises a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod, 
     wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, 
     wherein the collection vial is elongatable from the axially-compressed configuration, and 
     wherein the sampling device is configured such that proximal withdrawal of the shaft out of the internal plunger space, while the plunger head is within the tubular container, pulls the filter into the collection vial and elongates the collection vial. 
     Inventive Concept 114. The sampling device according to Inventive Concept 112, wherein the shaft is coupled to the plunger.
 
Inventive Concept 115. The sampling device according to Inventive Concept 114, wherein the sampling device is configured such that the shaft remains axially stationary with respect to the plunger head during the movement of the plunger head within the tubular container.
 
Inventive Concept 116. The sampling device according to Inventive Concept 114, wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, and wherein the shaft is slidable through the plunger-head opening.
 
Inventive Concept 117. The sampling device according to Inventive Concept 116, wherein the plunger-head opening forms a fluid-tight movable seal with an outer surface of the shaft.
 
Inventive Concept 118. The sampling device according to any one of Inventive Concepts 92-96,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, 
     wherein the sampling device further comprises a fluid-tight frangible seal, and 
     wherein the collection vial is positioned distal to the filter such that the frangible seal removably blocks liquid flow into the vial opening. 
     Inventive Concept 119. The sampling device according to Inventive Concept 118, further comprising a liquid that is contained in the collection vial, for bathing the filter within the collection vial.
 
Inventive Concept 120. The sampling device according to Inventive Concept 119, wherein the liquid is selected from the group consisting of: a lysis buffer, saline solution, and transport medium.
 
Inventive Concept 121. The sampling device according to Inventive Concept 118,
 
     wherein the filtration assembly further comprises a filter support, which is disposed within the tubular container, 
     wherein the filter support is shaped so as to define:
         (a) a proximal support surface,   (b) a plurality of filtrate-passage openings through the filter support, and   (c) a filter-support shaft-passage region,       

     wherein the filter is disposed on the proximal support surface, and 
     wherein the collection vial is positioned distal to the filter such that the frangible seal removably blocks liquid flow through the filter-support shaft-passage region into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the filter-support shaft-passage region. 
     Inventive Concept 122. The sampling device according to Inventive Concept 121, wherein the filter-support shaft-passage region is shaped so as to define a filter-support opening through the filter support.
 
Inventive Concept 123. The sampling device according to Inventive Concept 122, wherein the proximal portion of the shaft is positioned within the filter-support opening, releasably coupled to the filter support by one or more frangible portions of the filtration assembly.
 
Inventive Concept 124. The sampling device according to Inventive Concept 121, wherein the filter-support shaft-passage region is at least partially frangible, and wherein the filter support and the shaft are configured such that axial movement of the proximal portion of the shaft through the filter-support shaft-passage region forms a filter-support opening through the filter support.
 
Inventive Concept 125. The sampling device according to Inventive Concept 124, wherein the filter-support shaft-passage region comprises a frangible membrane.
 
Inventive Concept 126. The sampling device according to Inventive Concept 124, wherein the filter-support shaft-passage region is integral with other portions of the filter support and is thinner than the other portions of the filter support.
 
Inventive Concept 127. The sampling device according to Inventive Concept 121, further comprising a waste liquid receptacle downstream of the filter support, wherein the filter support is shaped so as to define the filtrate-passage openings through the filter support into the waste liquid receptacle.
 
Inventive Concept 128. The sampling device according to Inventive Concept 127, wherein the filter support is not shaped so as to define the filter-support shaft-passage region into the waste liquid receptacle.
 
Inventive Concept 129. The sampling device according to Inventive Concept 121, wherein the collection vial is disengageably coupled to the filter support of the filtration assembly.
 
Inventive Concept 130. The sampling device according to Inventive Concept 121, wherein a cross-sectional area of the filter-support shaft-passage region is between 2.5% and 20% of a cross-sectional area of the proximal support surface of the filter support.
 
Inventive Concept 131. The sampling device according to Inventive Concept 121,
 
     wherein the sampling device further comprises a shaft, and 
     wherein the filter support and the shaft are configured such that that a distal portion of the shaft is axially movable through the filter-support shaft-passage region and the vial opening so as to breach the frangible seal and advance the filter into the collection vial via the vial opening. 
     Inventive Concept 132. The sampling device according to Inventive Concept 131, 
     wherein the plunger comprises a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space, and 
     wherein the shaft is slidably disposed at least partially within the internal plunger space. 
     Inventive Concept 133. The sampling device according to Inventive Concept 132, 
     wherein a proximal end of the plunger rod is shaped so as to define a proximal opening of the internal plunger space, and 
     wherein a proximal portion of the shaft is accessible via the proximal opening of the internal plunger space. 
     Inventive Concept 134. The sampling device according to Inventive Concept 131, wherein a cross-sectional area of the distal portion of the shaft is between 80% and 110% of a cross-sectional area of the filter-support shaft-passage region.
 
Inventive Concept 135. The sampling device according to any one of Inventive Concepts 92-106, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 136. The sampling device according to Inventive Concept 135, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 137. The sampling device according to Inventive Concept 135, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly without any proximal withdrawal of the plunger head within the tubular container.
 
Inventive Concept 138. The sampling device according to any one of Inventive Concepts 92-106, wherein the sampling device is configured such that the collection vial is decouplable from the filtration assembly by distal movement of the collection vial with respect to the tubular container.
 
Inventive Concept 139. The sampling device according to any one of Inventive Concepts 92-106, further comprising a waste liquid receptacle, wherein the collection vial is disposed at least partially alongside the waste liquid receptacle.
 
Inventive Concept 140. The sampling device according to Inventive Concept 139, wherein the collection vial extends distally beyond a distal end of the waste liquid receptacle.
 
Inventive Concept 141. The sampling device according to Inventive Concept 139, wherein the waste liquid receptacle surrounds the collection vial.
 
Inventive Concept 142. The sampling device according to Inventive Concept 141, wherein the collection vial extends distally beyond a distal end of the waste liquid receptacle.
 
Inventive Concept 143. The sampling device according to any one of Inventive Concepts 92-96,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the sampling device further comprises a collection vial cap, which is configured to seal the vial opening. 
     Inventive Concept 144. A testing kit comprising the sampling device according to any one of Inventive Concepts 92-106, the testing kit further comprising a liquid selected from the group consisting of: a lysis buffer, saline solution, and transport medium, for bathing the filter within the collection vial.
 
Inventive Concept 145. A testing kit comprising the sampling device according to any one of Inventive Concepts 92-106, the testing kit further comprising a lateral flow immunoassay test strip, which is configured to detect the presence of a biological particulate trapped by the filter.
 
Inventive Concept 146. The testing kit according to Inventive Concept 145, further comprising reagents for use with the lateral flow immunoassay test strip.
 
Inventive Concept 147. The testing kit according to Inventive Concept 145, wherein the biological particulate is selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen.
 
Inventive Concept 148. The testing kit according to Inventive Concept 144, wherein the collection vial comprises an internal chamber, which contains the liquid and is configured to prevent spillage of the liquid out of the collection vial regardless of an orientation of the collection vial.
 
Inventive Concept 149. The testing kit according to Inventive Concept 148,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the testing kit further comprises a collection vial cap, which is configured to seal the vial opening, wherein the collection vial and the collection vial cap are configured such that placement of the collection vial cap on the vial opening automatically releases the liquid from the internal chamber. 
     Inventive Concept 150. The testing kit according to Inventive Concept 149, wherein the collection vial cap comprises a shaft that extends from an inner surface of the collection vial cap, and is configured to puncture the internal chamber when the collection vial cap is placed on the vial opening.
 
Inventive Concept 151. The sampling device according to any one of Inventive Concepts 92-96,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, 
     wherein the filtration assembly comprises a filter support, which is disposed within the tubular container, and is shaped so as to define: (a) a proximal support surface, (b) a plurality of filtrate-passage openings through the filter support, and (c) a filter-support shaft-passage region, 
     wherein the filter is disposed on the proximal support surface, 
     wherein the filtration assembly comprises a shaft, 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening, and 
     wherein the plunger head, the filter support, and the shaft are configured such that a proximal portion of the shaft is axially movable through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     Inventive Concept 152. The sampling device according to Inventive Concept 151, wherein the filter-support shaft-passage region is shaped so as to define a filter-support opening through the filter support.
 
Inventive Concept 153. The sampling device according to Inventive Concept 152, wherein the proximal portion of the shaft is positioned within the filter-support opening, releasably coupled to the filter support by one or more frangible portions of the filtration assembly.
 
Inventive Concept 154. The sampling device according to Inventive Concept 151, wherein the filter-support shaft-passage region is at least partially frangible, and wherein the filter support and the shaft are configured such that axial movement of the proximal portion of the shaft through the filter-support shaft-passage region forms a filter-support opening through the filter support.
 
Inventive Concept 155. The sampling device according to Inventive Concept 154, wherein the filter-support shaft-passage region comprises a frangible membrane.
 
Inventive Concept 156. The sampling device according to Inventive Concept 154, wherein the filter-support shaft-passage region is integral with other portions of the filter support and is thinner than the other portions of the filter support.
 
Inventive Concept 157. The sampling device according to any one of Inventive Concepts 92-106,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, 
     wherein the filtration assembly comprises a fluid-tight frangible seal, and 
     wherein the collection vial is disengageably coupled to the plunger and positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into a vial opening of the collection vial, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 158. The sampling device according to Inventive Concept 157, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 159. The sampling device according to Inventive Concept 158, wherein the sampling device is configured such that distal advancement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 160. The sampling device according to any one of Inventive Concepts 92-106, for use on the Earth,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, and 
     wherein the collection vial is (i) positioned proximal to the plunger head such that a vial opening of the collection vial is in fluid communication with the plunger-head opening, and (ii) configured to prevent escape of air from the collection vial as pressure builds up in the collection vial during distal advancement of the plunger head in the tubular container while the sampling device is oriented such that the proximal container opening faces upward away from the Earth. 
     Inventive Concept 161. The sampling device according to any one of Inventive Concepts 92-106, 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, 
     wherein the collection vial is positioned proximal to the plunger head, and 
     wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening. 
     Inventive Concept 162. The sampling device according to Inventive Concept 161, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 163. The sampling device according to Inventive Concept 161,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 164. The sampling device according to Inventive Concept 161, 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the sampling device further comprises a fluid-tight frangible seal, wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     There is additionally provided, in accordance with an Inventive Concept 165 of the present invention, a method for concentrating a liquid specimen sample, the method comprising: 
     placing the liquid specimen sample in a tubular container of a filtration assembly of a sampling device; 
     inserting a plunger head of a plunger of the filtration assembly into the tubular container via a proximal container opening of the tubular container, while a collection vial is disengageably coupled to the filtration assembly, such that a lateral surface of the plunger head forms a fluid-tight movable seal with an inner wall of the tubular container; 
     distally advancing the plunger head within the tubular container to drive at least a portion of the liquid specimen sample through a filter of the filtration assembly; 
     advancing the filter into the collection vial while the collection vial is disengageably coupled to the filtration assembly; and 
     thereafter, decoupling the collection vial from the filtration assembly. 
     Inventive Concept 166. The method according to Inventive Concept 165, wherein the filter is disposed within the tubular container before the liquid specimen sample is placed in the tubular container, and wherein placing the liquid specimen sample in the tubular container comprises placing the liquid specimen sample in the tubular container proximal to the filter that is disposed within the tubular container.
 
Inventive Concept 167. The method according to Inventive Concept 165, wherein advancing the filter into the collection vial comprises advancing the filter entirely into the collection vial while the collection vial is disengageably coupled to the filtration assembly.
 
Inventive Concept 168. The method according to Inventive Concept 165, wherein the collection vial is not shaped so as to define any pressure-release openings and does not comprise any pressure-release valves.
 
Inventive Concept 169. The method according to Inventive Concept 165,
 
     wherein the plunger comprises a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod, and 
     wherein decoupling the collection vial from the filtration assembly comprises removing the collection vial from the filtration assembly via the plunger-space proximal opening while the plunger head is within the tubular container. 
     Inventive Concept 170. The method according to Inventive Concept 169, 
     wherein the plunger rod is shaped so as to define therewithin a waste liquid receptacle, 
     wherein the plunger head is shaped so as to define a filter support, which is shaped so as to define (a) a distal support surface, (b) a plurality of filtrate-passage openings through the filter support into the waste liquid receptacle, and (c) the plunger-head opening, 
     wherein the filter is disposed on the distal support surface, and 
     wherein distally advancing the plunger head within the tubular container pushes at least a portion of the liquid specimen sample through the filter and the filtrate-passage openings and into the waste liquid receptacle. 
     Inventive Concept 171. The method according to Inventive Concept 169, wherein the collection vial is removably disposed at least partially within the internal plunger space.
 
Inventive Concept 172. The method according to Inventive Concept 171,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the collection vial is shaped so as to define a vial opening and a shaft-passage hole at an end of the collection vial opposite the vial opening, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial via the plunger-head opening and the vial opening while the collection vial is disengageably coupled to the filtration assembly, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) is disposed partially within the collection vial within the internal plunger space, (b) includes a proximal portion that is slidably disposed passing through the shaft-passage hole, and (c) includes a distal portion that is directly or indirectly coupled to the filter, and 
     wherein advancing the filter into the collection vial comprises proximally withdrawing the filter-withdrawal shaft, while the plunger head is within the tubular container, so as to pull the filter into the collection vial via the plunger-head opening and the vial opening. 
     Inventive Concept 173. The method according to Inventive Concept 171, 
     wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, and 
     wherein the method further comprises elongating the collection vial from the axially-compressed configuration. 
     Inventive Concept 174. The method according to Inventive Concept 173, wherein a wall of the collection vial is accordion-shaped.
 
Inventive Concept 175. The method according to Inventive Concept 171, wherein the collection vial includes a flexible material and is removably disposed at least partially within the internal plunger space while the collection vial is an inverted configuration, in which the inverted collection vial defines a proximal vial opening.
 
Inventive Concept 176. The method according to Inventive Concept 175, wherein the inverted configuration is a double-inverted configuration.
 
Inventive Concept 177. The method according to Inventive Concept 175,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head and into the internal plunger space, 
     wherein the sampling device comprises a filter-withdrawal shaft, which (a) is disposed partially within the inverted collection vial within the internal plunger space, and (b) includes a distal portion that is directly or indirectly coupled to the filter, 
     wherein removing the filter from the tubular container comprises proximally withdrawing the filter-withdrawal shaft out of the internal plunger space, while the plunger head is within the tubular container, so as to invert the inverted collection vial to an uninverted configuration, to pull the filter into the collection vial via the plunger-head opening, to pull the collection vial out of the internal plunger space via the plunger-space proximal opening, and to remove the filter-withdrawal shaft and the filter from the filtration assembly. 
     Inventive Concept 178. The method according to Inventive Concept 165, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial via a vial opening of the collection vial while the collection vial is disengageably coupled to the filtration assembly.
 
Inventive Concept 179. The method according to any one of Inventive Concepts 165-178, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial while the plunger head is within the tubular container.
 
Inventive Concept 180. The method according to Inventive Concept 179, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 181. The method according to Inventive Concept 179, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial without proximally withdrawing the plunger head within the tubular container.
 
Inventive Concept 182. The method according to any one of Inventive Concepts 165-178, wherein the filtration assembly is configured such that when the plunger head is within the tubular container, fluid communication is blocked between (a) the tubular container distal to the plunger head and (b) the proximal container opening.
 
Inventive Concept 183. The method according to Inventive Concept 182, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial while the plunger head is within the tubular container.
 
Inventive Concept 184. The method according to any one of Inventive Concepts 165-168, wherein the collection vial is disengageably coupled to the tubular container of the filtration assembly.
 
Inventive Concept 185. The method according to any one of Inventive Concepts 165-168,
 
     wherein the sampling device further includes a shaft, and 
     wherein advancing the filter into the collection vial comprises axially moving a distal portion of the shaft through a vial opening of the collection vial so as to advance the filter into the collection vial via the vial opening. 
     Inventive Concept 186. The method according to Inventive Concept 185, 
     wherein the plunger comprises a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space having a plunger-space proximal opening through a proximal end of the plunger rod, 
     wherein the collection vial is removably disposed at least partially within the internal plunger space while the collection vial is an axially-compressed configuration, 
     wherein the collection vial is elongatable from the axially-compressed configuration, and 
     wherein advancing the filter into the collection vial comprises proximally withdrawing the shaft out of the internal plunger space, while the plunger head is within the tubular container, so as to pull the filter into the collection vial and to elongate the collection vial. 
     Inventive Concept 187. The method according to Inventive Concept 185, wherein the shaft is coupled to the plunger.
 
Inventive Concept 188. The method according to Inventive Concept 187, wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head within the tubular container while the shaft remains axially stationary with respect to the plunger head.
 
Inventive Concept 189. The method according to Inventive Concept 187, wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, and wherein the shaft is slidable through the plunger-head opening.
 
Inventive Concept 190. The method according to Inventive Concept 189, wherein the plunger-head opening forms a fluid-tight movable seal with an outer surface of the shaft.
 
Inventive Concept 191. The method according to any one of Inventive Concepts 165-168,
 
     wherein the sampling device further includes a fluid-tight frangible seal, and 
     wherein the collection vial is positioned distal to the filter such that the frangible seal removably blocks liquid flow into a vial opening of the collection vial. 
     Inventive Concept 192. The method according to Inventive Concept 191, further comprising a liquid that is contained in the collection vial, for bathing the filter within the collection vial.
 
Inventive Concept 193. The method according to Inventive Concept 192, wherein the liquid is selected from the group consisting of: a lysis buffer, saline solution, and transport medium.
 
Inventive Concept 194. The method according to Inventive Concept 191,
 
     wherein the filtration assembly further includes a filter support, which is disposed within the tubular container, 
     wherein the filter support is shaped so as to define:
         (a) a proximal support surface,   (b) a plurality of filtrate-passage openings through the filter support, and   (c) a filter-support shaft-passage region,       

     wherein the filter is disposed on the proximal support surface, and 
     wherein the collection vial is positioned distal to the filter such that the frangible seal removably blocks liquid flow through the filter-support shaft-passage region into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the filter-support shaft-passage region. 
     Inventive Concept 195. The method according to Inventive Concept 194, wherein the filter-support shaft-passage region is shaped so as to define a filter-support opening through the filter support.
 
Inventive Concept 196. The method according to Inventive Concept 195, wherein the proximal portion of the shaft is positioned within the filter-support opening, releasably coupled to the filter support by one or more frangible portions of the filtration assembly.
 
Inventive Concept 197. The method according to Inventive Concept 194, wherein the filter-support shaft-passage region is at least partially frangible, and wherein the filter support and the shaft are configured such that axial movement of the proximal portion of the shaft through the filter-support shaft-passage region forms a filter-support opening through the filter support.
 
Inventive Concept 198. The method according to Inventive Concept 197, wherein the filter-support shaft-passage region comprises a frangible membrane.
 
Inventive Concept 199. The method according to Inventive Concept 197, wherein the filter-support shaft-passage region is integral with other portions of the filter support and is thinner than the other portions of the filter support.
 
Inventive Concept 200. The method according to Inventive Concept 194, further comprising a waste liquid receptacle downstream of the filter support, wherein the filter support is shaped so as to define the filtrate-passage openings through the filter support into the waste liquid receptacle.
 
Inventive Concept 201. The method according to Inventive Concept 200, wherein the filter support is not shaped so as to define the filter-support shaft-passage region into the waste liquid receptacle.
 
Inventive Concept 202. The method according to Inventive Concept 194, wherein the collection vial is disengageably coupled to the filter support of the filtration assembly.
 
Inventive Concept 203. The method according to Inventive Concept 194,
 
     wherein the sampling device further includes a shaft, and 
     wherein advancing the filter into the collection vial comprises axially moving a distal portion of the shaft through the filter-support shaft-passage region and the vial opening so as to breach the frangible seal and advance the filter into the collection vial via the vial opening. 
     Inventive Concept 204. The method according to Inventive Concept 203, 
     wherein the plunger includes a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space, and 
     wherein the shaft is slidably disposed at least partially within the internal plunger space. 
     Inventive Concept 205. The method according to Inventive Concept 204, 
     wherein a proximal end of the plunger rod is shaped so as to define a proximal opening of the internal plunger space, and 
     wherein the method further comprises accessing a proximal portion of the shaft via the proximal opening of the internal plunger space. 
     Inventive Concept 206. The method according to any one of Inventive Concepts 165-168, wherein decoupling the collection vial from the filtration assembly comprises decoupling the collection vial from the filtration assembly while the plunger head is within the tubular container.
 
Inventive Concept 207. The method according to Inventive Concept 206, wherein decoupling the collection vial from the filtration assembly comprises decoupling the collection vial from the filtration assembly while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 208. The method according to Inventive Concept 206, wherein decoupling the collection vial from the filtration assembly comprises decoupling the collection vial from the filtration assembly without proximally withdrawing the plunger head within the tubular container.
 
Inventive Concept 209. The method according to any one of Inventive Concepts 165-168, wherein decoupling the collection vial from the filtration assembly comprises distally moving the collection vial with respect to the tubular container.
 
Inventive Concept 210. The method according to any one of Inventive Concepts 165-178, wherein the sampling device further includes a waste liquid receptacle, and wherein the collection vial is disposed at least partially alongside the waste liquid receptacle.
 
Inventive Concept 211. The method according to Inventive Concept 210, wherein the collection vial extends distally beyond a distal end of the waste liquid receptacle.
 
Inventive Concept 212. The method according to Inventive Concept 210, wherein the waste liquid receptacle surrounds the collection vial.
 
Inventive Concept 213. The method according to Inventive Concept 212, wherein the collection vial extends distally beyond a distal end of the waste liquid receptacle.
 
Inventive Concept 214. The method according to any one of Inventive Concepts 165-168, further comprising sealing a vial opening of the collection vial with a collection vial cap after the filter has been advanced into the collection vial via the vial opening.
 
Inventive Concept 215. The method according to any one of Inventive Concepts 165-178, further comprising bathing the filter with a liquid within the collection vial after the filter has been advanced into the collection vial.
 
Inventive Concept 216. The method according to Inventive Concept 215, wherein the liquid is selected from the group consisting of: a lysis buffer, saline solution, and transport medium.
 
Inventive Concept 217. The method according to Inventive Concept 215, wherein the collection vial includes an internal chamber, which contains the liquid and is configured to prevent spillage of the liquid out of the collection vial regardless of an orientation of the collection vial.
 
Inventive Concept 218. The method according to Inventive Concept 217, further comprising, after the filter has been advanced into the collection vial via a vial opening of the collection vial, sealing the vial opening with a collection vial cap so as to automatically release the liquid from the internal chamber.
 
Inventive Concept 219. The method according to Inventive Concept 218, wherein the collection vial cap includes a shaft that extends from an inner surface of the collection vial cap, and is configured to puncture the internal chamber when the collection vial cap is placed on the vial opening.
 
Inventive Concept 220. The method according to any one of Inventive Concepts 165-168, further comprising, after the filter has been advanced into the collection vial, detecting the presence of a biological particulate trapped by the filter.
 
Inventive Concept 221. The method according to Inventive Concept 220, wherein detecting the presence of the biological particulate trapped by the filter comprising using a lateral flow immunoassay test strip to detect the presence of the biological particulate trapped by the filter.
 
Inventive Concept 222. The method according to Inventive Concept 220, wherein the biological particulate is selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen.
 
Inventive Concept 223. The method according to any one of Inventive Concepts 165-178,
 
     wherein the plunger head is shaped so as to define a plunger-head opening through the plunger head, 
     wherein the collection vial is positioned proximal to the plunger head, and 
     wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head and the collection vial within the tubular container so as to advance the filter into the collection vial via the plunger-head opening. 
     Inventive Concept 224. The method according to Inventive Concept 223, wherein distally advancing the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 225. The method according to Inventive Concept 223,
 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 226. The method according to Inventive Concept 223, 
     wherein the collection vial is shaped so as to define a vial opening, and wherein the sampling device is configured such that the filter is advanceable into the collection vial via the vial opening while the collection vial is disengageably coupled to the filtration assembly, and 
     wherein the sampling device further includes a fluid-tight frangible seal, and wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     There is yet additionally provided, in accordance with an Inventive Concept 227 of the present invention, a sampling device for concentrating a liquid specimen sample, the sampling device comprising: 
     (a) a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define a proximal container opening and an inner wall;   (ii) a plunger, which (A) comprises a plunger head, which is shaped so as to define a plunger-head opening through the plunger head, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall;   (iii) a filter support, which is disposed within the tubular container, and is shaped so as to define: (A) a proximal support surface, (B) a plurality of filtrate-passage openings through the filter support, and (C) a filter-support shaft-passage region;   (iv) a filter, which is disposed on the proximal support surface; and   (v) a shaft; and       

     (b) a collection vial, which is positioned proximal to the plunger head such that a vial opening of the collection vial is in fluid communication with the plunger-head opening, 
     wherein the plunger head, the filter support, and the shaft are configured such that a proximal portion of the shaft is axially movable through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     There is also provided, in accordance with an Inventive Concept 228 of the present invention, a sampling device for concentrating a liquid specimen sample, the sampling device comprising: 
     (a) a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define a proximal container opening and an inner wall; and   (ii) a plunger, which (A) comprises a plunger head, which is shaped so as to define a plunger-head opening through the plunger head, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall;       

     (b) a fluid-tight frangible seal; and 
     (c) a collection vial, which is disengageably coupled to the plunger and positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into a vial opening of the collection vial, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 229. The sampling device according to Inventive Concept 228, wherein the filtration assembly further comprises a filter disposed within the tubular container.
 
Inventive Concept 230. The sampling device according to Inventive Concept 229, wherein the plunger is insertable into the tubular container from outside the tubular container via the proximal container opening while the filter is disposed within the tubular container.
 
Inventive Concept 231. The sampling device according to Inventive Concept 229, wherein the sampling device is configured such that movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 232. The sampling device according to Inventive Concept 231, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter entirely into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 233. The sampling device according to Inventive Concept 231, wherein the sampling device is configured such that distal advancement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 234. The sampling device according to Inventive Concept 233, wherein the sampling device is configured such that the distal advancement of the plunger head and the collection vial within the tubular container advances the filter entirely into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 235. The sampling device according to Inventive Concept 228, wherein the filtration assembly further comprises:
 
     a filter support, which is disposed within the tubular container, and is shaped so as to define: (a) a proximal support surface, and (b) a plurality of filtrate-passage openings through the filter support; and 
     a filter, which is disposed on the proximal support surface. 
     Inventive Concept 236. The sampling device according to Inventive Concept 235, further comprising a shaft, 
     wherein the filter support is shaped so as to define a filter-support shaft-passage region, and 
     wherein the plunger head, the filter support, and the shaft are configured such that a proximal portion of the shaft is axially movable through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     There is further provided, in accordance with an Inventive Concept 237 of the present invention, a sampling device for concentrating a liquid specimen sample, for use on the Earth, the sampling device comprising: 
     (a) a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define a proximal container opening and an inner wall; and   (ii) a plunger, which (A) comprises a plunger head, which is shaped so as to define a plunger-head opening through the plunger head, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall; and       

     (b) a collection vial, which is (i) positioned proximal to the plunger head such that a vial opening of the collection vial is in fluid communication with the plunger-head opening, and (ii) configured to prevent escape of air from the collection vial as pressure builds up in the collection vial during distal advancement of the plunger head in the tubular container while the sampling device is oriented such that the proximal container opening faces upward away from the Earth. 
     Inventive Concept 238. The sampling device according to Inventive Concept 237, wherein the filtration assembly further comprises a filter disposed within the tubular container.
 
Inventive Concept 239. The sampling device according to Inventive Concept 238, wherein the plunger is insertable into the tubular container from outside the tubular container via the proximal container opening while the filter is disposed within the tubular container.
 
Inventive Concept 240. The sampling device according to Inventive Concept 238, wherein the sampling device is configured such that movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 241. The sampling device according to Inventive Concept 240, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter entirely into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 242. The sampling device according to Inventive Concept 240, wherein the sampling device is configured such that distal advancement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 243. The sampling device according to Inventive Concept 242, wherein the sampling device is configured such that the distal advancement of the plunger head and the collection vial within the tubular container advances the filter entirely into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 244. The sampling device according to Inventive Concept 237, wherein the filtration assembly further comprises:
 
     a filter support, which is disposed within the tubular container, and is shaped so as to define: (a) a proximal support surface, and (b) a plurality of filtrate-passage openings through the filter support; and 
     a filter, which is disposed on the proximal support surface. 
     Inventive Concept 245. The sampling device according to Inventive Concept 244, further comprising a shaft, 
     wherein the filter support is shaped so as to define a filter-support shaft-passage region, and 
     wherein the plunger head, the filter support, and the shaft are configured such that a proximal portion of the shaft is axially movable through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     There is still further provided, in accordance with an Inventive Concept 246 of the present invention, a sampling device for concentrating a liquid specimen sample, the sampling device comprising: 
     (a) a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define a proximal container opening and an inner wall;   (ii) a plunger, which (A) comprises a plunger head, which is shaped so as to define a plunger-head opening through the plunger head, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall; and   (iii) a filter; and       

     (b) a collection vial, which is positioned proximal to the plunger head, and is shaped so as to define a vial opening, 
     wherein the sampling device is configured such that movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening. 
     Inventive Concept 247. The sampling device according to Inventive Concept 246, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter entirely into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 248. The sampling device according to Inventive Concept 246, wherein the sampling device is configured such that the movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 249. The sampling device according to Inventive Concept 246, wherein the sampling device is configured such that distal advancement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 250. The sampling device according to Inventive Concept 249, wherein the sampling device is configured such that the distal advancement of the plunger head and the collection vial within the tubular container advances the filter entirely into the collection vial via the plunger-head opening and the vial opening.
 
Inventive Concept 251. The sampling device according to Inventive Concept 246, wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening.
 
Inventive Concept 252. The sampling device according to Inventive Concept 251, wherein the collection vial is configured to prevent escape of air from the collection vial as pressure builds up in the collection vial during distal advancement of the plunger head in the tubular container while the sampling device is oriented such that the proximal container opening faces upward away from the Earth.
 
Inventive Concept 253. The sampling device according to Inventive Concept 246, further comprising a fluid-tight frangible seal, wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening.
 
Inventive Concept 254. The sampling device according to Inventive Concept 253, wherein the collection vial is disengageably coupled to the plunger.
 
Inventive Concept 255. The sampling device according to Inventive Concept 246, wherein the filter is disposed within the tubular container.
 
Inventive Concept 256. The sampling device according to Inventive Concept 255, wherein the plunger is insertable into the tubular container from outside the tubular container via the proximal container opening while the filter is disposed within the tubular container.
 
Inventive Concept 257. The sampling device according to Inventive Concept 255,
 
     wherein the filtration assembly further comprises a filter support, which is disposed within the tubular container, and is shaped so as to define: (a) a proximal support surface, and (b) a plurality of filtrate-passage openings through the filter support, and 
     wherein the filter is disposed on the proximal support surface. 
     Inventive Concept 258. The sampling device according to Inventive Concept 257, further comprising a shaft, 
     wherein the filter support is shaped so as to define a filter-support shaft-passage region, and 
     wherein the plunger head, the filter support, and the shaft are configured such that a proximal portion of the shaft is axially movable through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     Inventive Concept 259. The sampling device according to Inventive Concept 258, 
     wherein the sampling device further comprises a fluid-tight frangible seal, 
     wherein the collection vial is positioned proximal to the plunger head such that the frangible seal removably blocks liquid flow from the plunger-head opening into the vial opening, such that upon breaching of the frangible seal the vial opening is in fluid communication with the plunger-head opening, 
     wherein the sampling device is configured such that:
         movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening, and   relative axial movement between the shaft and the collection vial causes the proximal portion of the shaft to breach the frangible seal and push the filter into the collection vial via the vial opening.
 
Inventive Concept 260. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein the filter-support shaft-passage region is shaped so as to define a filter-support opening through the filter support.
 
Inventive Concept 261. The sampling device according to Inventive Concept 260, wherein the proximal portion of the shaft is positioned within the filter-support opening, releasably coupled to the filter support by one or more frangible portions of the filtration assembly.
 
Inventive Concept 262. The sampling device according to Inventive Concept 260, wherein a proximal end of the proximal portion of the shaft is positioned within the filter-support opening.
 
Inventive Concept 263. The sampling device according to Inventive Concept 260, wherein the proximal portion of the shaft is positioned within the filter-support opening such that a proximal end of the proximal portion of the shaft is flush with the proximal support surface.
 
Inventive Concept 264. The sampling device according to Inventive Concept 260, wherein the proximal portion of the shaft is positioned within the filter-support opening such that a proximal end of the proximal portion of the shaft protrudes proximally from the support surface of the filter support.
 
Inventive Concept 265. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein the filter-support shaft-passage region is at least partially frangible, and wherein the filter support and the shaft are configured such that axial movement of the proximal portion of the shaft through the filter-support shaft-passage region forms a filter-support opening through the filter support.
 
Inventive Concept 266. The sampling device according to Inventive Concept 265, wherein the filter-support shaft-passage region comprises a frangible membrane.
 
Inventive Concept 267. The sampling device according to Inventive Concept 265, wherein the filter-support shaft-passage region is integral with other portions of the filter support and is thinner than the other portions of the filter support.
 
Inventive Concept 268. The sampling device according to any one of Inventive Concepts 227, 228, 237, and 246, wherein the collection vial is not shaped so as to define any pressure-release openings and does not comprise any pressure-release valves.
 
Inventive Concept 269. The sampling device according to any one of Inventive Concepts 227, 228, 237, and 246, wherein the filtration assembly is configured such that when the plunger head is within the tubular container, fluid communication is blocked between (a) the tubular container distal to the plunger head and (b) the proximal container opening.
 
Inventive Concept 270. The sampling device according to any one of Inventive Concepts 227, 229, 235, 238, 244, and 246,
       

     wherein the filtration assembly is configured such that when the plunger head is within the tubular container, fluid communication is blocked between (a) the tubular container distal to the plunger head and (b) the proximal container opening, and 
     wherein the filter is advanceable into the collection vial while the plunger head is within the tubular container. 
     Inventive Concept 271. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein a proximal end of the proximal portion of the shaft is positioned within the tubular container distal to the filter-support shaft-passage region.
 
Inventive Concept 272. The sampling device according to any one of Inventive Concepts 227, 235-236, 244-245, and 257-258, wherein the filter support is slidable along the tubular container.
 
Inventive Concept 273. The sampling device according to Inventive Concept 272, wherein a lateral surface of the filter support is configured to form a fluid-tight movable seal with the inner wall of the tubular container.
 
Inventive Concept 274. The sampling device according to Inventive Concept 272, wherein the sampling device is configured such that:
 
     first distal advancement of the plunger head within the tubular container, when the liquid specimen sample is contained in the tubular container and the filter is disposed in the tubular container, pushes at least a portion of the liquid specimen sample through the filter, without pushing the filter support distally within the tubular container, and 
     further second distal advancement of the plunger head pushes the filter support distally within the tubular container. 
     Inventive Concept 275. The sampling device according to Inventive Concept 274, wherein the sampling device is configured such that the further second distal advancement of the plunger head pushes the filter support distally within the tubular container in the absence of a filter-support release action by a user.
 
Inventive Concept 276. The sampling device according to Inventive Concept 274, wherein the sampling device is configured such that the further second distal advancement of the plunger head pushes the filter support distally within the tubular container with respect to the shaft, such that the proximal portion of the shaft pushes the filter through the filter-support shaft-passage region, the plunger-head opening, and the vial opening, into the collection vial.
 
Inventive Concept 277. The sampling device according to Inventive Concept 276, wherein the filter support and the shaft are releasably coupled to each other such that:
 
     the first distal advancement of the plunger head within the tubular container does not decouple the filter support from the shaft, and 
     the further second distal advancement of the plunger head decouples the filter support from the shaft. 
     Inventive Concept 278. The sampling device according to Inventive Concept 277, wherein the proximal portion of the shaft is releasably coupled to the filter support by one or more frangible portions of the filtration assembly.
 
Inventive Concept 279. The sampling device according to Inventive Concept 276, wherein the filter support and the shaft are releasably axially locked with respect to each other such that:
 
     the first distal advancement of the plunger head within the tubular container does not axially unlock the filter support and the shaft with respect to each other, and 
     the further second distal advancement of the plunger head axially unlocks the filter support and the shaft with respect to each other, thereby enabling axial movement with respect to each other. 
     Inventive Concept 280. The sampling device according to Inventive Concept 279, wherein the filtration assembly comprises one or more release controls, which are configured to axially unlock the filter support and the shaft with respect to each other upon actuation of the one or more release controls by the further second distal advancement of the plunger head.
 
Inventive Concept 281. The sampling device according to Inventive Concept 274, wherein the plunger comprises a plunger rod, which has a distal end portion to which the plunger head is disengageably coupled.
 
Inventive Concept 282. The sampling device according to Inventive Concept 281, wherein the sampling device is configured such that the plunger head becomes decoupled from the plunger rod as the plunger head distally pushes the filter support within the tubular container.
 
Inventive Concept 283. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein the sampling device is configured such that:
 
     movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and the vial opening, and 
     relative axial movement between the shaft and the collection vial causes the proximal portion of the shaft to push the filter into the collection vial via the vial opening. 
     Inventive Concept 284. The sampling device according to any one of Inventive Concepts 227-258, wherein a cross-sectional area of the plunger-head opening is between 20% and 90% of a cross-sectional area of a distal surface of the plunger head.
 
Inventive Concept 285. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein a cross-sectional area of the filter-support shaft-passage region is between 2.5% and 20% of a cross-sectional area of the proximal support surface of the filter support.
 
Inventive Concept 286. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein a cross-sectional area of the proximal portion of the shaft is between 80% and 110% of a cross-sectional area of the filter-support shaft-passage region.
 
Inventive Concept 287. The sampling device according to any one of Inventive Concepts 227-258, wherein the collection vial has a volume of between 1 and 50 ml.
 
Inventive Concept 288. The sampling device according to any one of Inventive Concepts 227, 237-245, and 246-258, wherein the collection vial is disengageably coupled to the plunger.
 
Inventive Concept 289. The sampling device according to any one of Inventive Concepts 228-236 and 288, wherein the sampling device is configured such that the collection vial is decouplable from the plunger while the plunger head is within the tubular container.
 
Inventive Concept 290. The sampling device according to Inventive Concept 289, wherein the sampling device is configured such that the collection vial is decouplable from the plunger via a proximal end of the plunger.
 
Inventive Concept 291. The sampling device according to Inventive Concept 289, wherein the sampling device is configured such that the collection vial is decouplable from the plunger while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 292. The sampling device according to Inventive Concept 289, wherein the sampling device is configured such that the collection vial is decouplable from the plunger without any proximal withdrawal of the plunger head within the tubular container.
 
Inventive Concept 293. The sampling device according to any one of Inventive Concepts 228-236 and 288,
 
     wherein the plunger comprises a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space, and 
     wherein the collection vial is removably disposed at least partially within the internal plunger space. 
     Inventive Concept 294. The sampling device according to Inventive Concept 293, 
     wherein a proximal end of the plunger rod is shaped so as to define a proximal opening of the internal plunger space, and 
     wherein the collection vial is removable from the internal plunger space through the proximal opening. 
     Inventive Concept 295. The sampling device according to Inventive Concept 294, wherein the sampling device comprises one or more couplers, which are configured to disengageably couple an external surface of the collection vial axially with respect to a proximal portion of the plunger rod.
 
Inventive Concept 296. The sampling device according to Inventive Concept 295, wherein the one or more couplers are configured to disengageably couple the external surface of the collection vial axially with respect to a flange defined by the proximal portion of the plunger rod.
 
Inventive Concept 297. The sampling device according to Inventive Concept 293, wherein the collection vial is removably disposed partially within the internal plunger space, with an axial portion of the collection vial protruding proximally out of the proximal opening, the axial portion of the collection vial including an end of the collection vial opposite an end of the collection vial that defines the vial opening.
 
Inventive Concept 298. The sampling device according to Inventive Concept 297, wherein the axial portion of the collection vial protrudes proximally out of the proximal opening by at least 4 cm.
 
Inventive Concept 299. The sampling device according to any one of Inventive Concepts 228-236 and 288,
 
     wherein the plunger comprises a plunger rod, which has a distal end portion to which the plunger head is coupled, and 
     wherein the collection vial is disposed alongside the plunger rod. 
     Inventive Concept 300. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein the proximal portion of the shaft is axially fixed with respect to the proximal container opening.
 
Inventive Concept 301. The sampling device according to Inventive Concept 300, wherein the filter support is slidable along the tubular container.
 
Inventive Concept 302. The sampling device according to any one of Inventive Concepts 227, 236, 245, and 258, wherein the proximal portion of the shaft is axially movable with respect to the proximal container opening.
 
Inventive Concept 303. The sampling device according to Inventive Concept 302, wherein the sampling device is configured to automatically axially move the shaft through the filter-support shaft-passage region, the plunger-head opening, and the vial opening.
 
Inventive Concept 304. The sampling device according to Inventive Concept 302, wherein the sampling device further comprises a spring, which is configured to axially move the proximal portion of the shaft with respect to the proximal container opening.
 
Inventive Concept 305. The sampling device according to Inventive Concept 302,
 
     wherein the tubular container includes a distal tubular portion that is distal to the filter support and is configured to have an adjustable length, and 
     wherein the sampling device is configured such that shortening of the adjustable length axially moves the shaft through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     Inventive Concept 306. The sampling device according to Inventive Concept 305, wherein the distal tubular portion is axially collapsible to provide the shortening of the length of the distal tubular portion.
 
Inventive Concept 307. The sampling device according to any one of Inventive Concepts 227-258, further comprising a collection vial cap, which is configured to seal the vial opening.
 
Inventive Concept 308. A testing kit comprising the sampling device according to any one of Inventive Concepts 227-258, the testing kit further comprising a liquid selected from the group consisting of: a lysis buffer, saline solution, and transport medium, for bathing the filter within the collection vial.
 
Inventive Concept 309. A testing kit comprising the sampling device according to any one of Inventive Concepts 227-245, the testing kit further comprising a lateral flow immunoassay test strip, which is configured to detect the presence of a biological particulate trapped by the filter.
 
Inventive Concept 310. The testing kit according to Inventive Concept 309, further comprising reagents for use with the lateral flow immunoassay test strip.
 
Inventive Concept 311. The testing kit according to Inventive Concept 309, wherein the biological particulate is selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen.
 
Inventive Concept 312. The testing kit according to Inventive Concept 308, wherein the collection vial comprises an internal chamber, which contains the liquid and is configured to prevent spillage of the liquid out of the collection vial regardless of an orientation of the collection vial.
 
Inventive Concept 313. The testing kit according to Inventive Concept 312, further comprising a collection vial cap, which is configured to seal the vial opening, wherein the collection vial and the collection vial cap are configured such that placement of the collection vial cap on the vial opening automatically releases the liquid from the internal chamber.
 
Inventive Concept 314. The testing kit according to Inventive Concept 313, wherein the collection vial cap comprises a shaft that extends from an inner surface of the collection vial cap, and is configured to puncture the internal chamber when the collection vial cap is placed on the vial opening.
 
     There is additionally provided, in accordance with an Inventive Concept 315 of the present invention, a sampling device for concentrating a liquid specimen sample, the sampling device comprising: 
     (a) a filtration assembly, which comprises:
         (i) a tubular container, which is shaped so as to define a proximal container opening and an inner wall;   (ii) a plunger, which (A) comprises a plunger head, which is shaped so as to define a plunger-head opening through the plunger head, and (B) is insertable into the tubular container via the proximal container opening, such that a lateral surface of the plunger head forms a fluid-tight movable seal with the inner wall; and   (iii) a filter; and       

     (b) a collection vial, which is positioned proximal to the plunger head, 
     wherein the sampling device is configured such that movement of the plunger head and the collection vial within the tubular container advances the filter into the collection vial via the plunger-head opening and a vial opening of the collection vial. 
     There is yet additionally provided, in accordance with an Inventive Concept 316 of the present invention, a method for concentrating a liquid specimen sample, the method comprising: 
     placing the liquid specimen sample in a tubular container of a filtration assembly of a sampling device, proximal to a filter that is disposed within the tubular container; 
     inserting a plunger head of a plunger of the filtration assembly into the tubular container via a proximal container opening of the tubular container, while a collection vial is positioned proximal to the plunger head, such that a lateral surface of the plunger head forms a fluid-tight movable seal with an inner wall of the tubular container; 
     distally advancing the plunger head within the tubular container to drive at least a portion of the liquid specimen sample through the filter; and 
     advancing the filter into the collection vial via (a) a plunger-head opening defined through the plunger head and (b) a vial opening of the collection vial. 
     Inventive Concept 317. The method according to Inventive Concept 316, wherein advancing the filter into the collection vial comprises advancing the filter entirely into the collection vial via the plunger-head opening and the vial opening of the collection vial.
 
Inventive Concept 318. The method according to Inventive Concept 316, wherein advancing the filter into the collection vial comprises advancing the filter into the collection vial while the filter remains stationary with respect to a distal end of the tubular container.
 
Inventive Concept 319. The method according to Inventive Concept 316, wherein advancing the filter into the collection vial via the plunger-head opening and the vial opening comprises moving the plunger head and the collection vial within the tubular container.
 
Inventive Concept 320. The method according to Inventive Concept 316, wherein advancing the filter into the collection vial via the plunger-head opening and the vial opening comprises axially moving a proximal portion of a shaft of the sampling device and the collection vial with respect to each other, such that (a) the proximal portion of the shaft moves through the plunger-head opening and the vial opening, and (a) a proximal end of the shaft pushes the filter through the plunger-head opening into the collection vial via the vial opening.
 
Inventive Concept 321. The method according to Inventive Concept 320, wherein the proximal portion of the shaft is axially fixed with respect to the proximal container opening.
 
Inventive Concept 322. The method according to Inventive Concept 316,
 
     wherein the collection vial is positioned proximal to the plunger head such that the vial opening is in fluid communication with the plunger-head opening, and 
     wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head within the tubular container, while the sampling device is oriented such that the proximal container opening faces upward away from the Earth, to drive the at least a portion of the liquid specimen sample through the filter. 
     Inventive Concept 323. The method according to Inventive Concept 316, 
     wherein the collection vial is positioned proximal to the plunger head such that a fluid-tight frangible seal of the sampling device removably blocks flow of the liquid specimen sample from the plunger-head opening into the vial opening, and 
     wherein advancing the filter into the collection vial via the plunger-head opening and the vial opening of the collection vial comprises breaching the frangible seal such that the vial opening is in fluid communication with the plunger-head opening. 
     Inventive Concept 324. The method according to any one of Inventive Concepts 316-323, 
     wherein placing the liquid specimen sample in the tubular container comprises placing the liquid specimen sample in the tubular container proximal to the filter that is disposed on a proximal support surface defined by a filter support that is disposed within the tubular container, and 
     wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head within the tubular container to drive the at least a portion of the liquid specimen sample through the filter and a plurality of filtrate-passage openings defined by the filter support. 
     Inventive Concept 325. The method according to Inventive Concept 324, wherein a lateral surface of the filter support is configured to form a fluid-tight movable seal with the inner wall of the tubular container.
 
Inventive Concept 326. The method according to Inventive Concept 324,
 
     wherein the filter support is slidable along the tubular container, 
     wherein the method further comprises, after distally advancing the plunger head within the tubular container to drive the at least a portion of the liquid specimen sample through the filter and the filtrate-passage openings of the filter support, further distally advancing the plunger head within the tubular container such that the plunger head distally pushes the filter support within the tubular container. 
     Inventive Concept 327. The method according to Inventive Concept 324, wherein advancing the filter into the collection vial via the plunger-head opening and the vial opening comprises axially moving a proximal portion of a shaft of the sampling device and the collection vial with respect to each other, such that (a) the proximal portion of the shaft moves through (i) a filter-support shaft-passage region defined by the filter support, (ii) the plunger-head opening, and (iii) the vial opening, and (a) a proximal end of the shaft pushes the filter through the plunger-head opening into the collection vial via the vial opening.
 
Inventive Concept 328. The method according to Inventive Concept 327, wherein the filter-support shaft-passage region is shaped so as to define a filter-support opening through the filter support.
 
Inventive Concept 329. The method according to Inventive Concept 328, wherein the proximal portion of the shaft is positioned within the filter-support opening, releasably coupled to the filter support by one or more frangible portions of the filtration assembly.
 
Inventive Concept 330. The method according to Inventive Concept 327, wherein the filter-support shaft-passage region is at least partially frangible, and wherein the filter support and the shaft are configured such that axial movement of the proximal portion of the shaft through the filter-support shaft-passage region forms a filter-support opening through the filter support.
 
Inventive Concept 331. The method according to Inventive Concept 330, wherein the filter-support shaft-passage region comprises a frangible membrane.
 
Inventive Concept 332. The method according to Inventive Concept 330, wherein the filter-support shaft-passage region is integral with other portions of the filter support and is thinner than the other portions of the filter support.
 
Inventive Concept 333. The method according to any one of Inventive Concepts 316-323, wherein the collection vial is disengageably coupled to the plunger, and wherein the method further comprises decoupling the collection vial from the plunger after advancing the filter into the collection vial.
 
Inventive Concept 334. The method according to Inventive Concept 333, wherein decoupling the collection vial from the plunger comprises decoupling the collection vial from the plunger while the plunger head is within the tubular container.
 
Inventive Concept 335. The method according to Inventive Concept 334, wherein decoupling the collection vial from the plunger comprises decoupling the collection vial from the plunger via a proximal end of the plunger.
 
Inventive Concept 336. The method according to Inventive Concept 334, wherein decoupling the collection vial from the plunger comprises decoupling the collection vial from the plunger while the plunger head is advanced as far as possible within the tubular container.
 
Inventive Concept 337. The method according to Inventive Concept 334, wherein decoupling the collection vial from the plunger comprises decoupling the collection vial from the plunger without proximally withdrawing the plunger head within the tubular container.
 
Inventive Concept 338. The method according to Inventive Concept 333,
 
     wherein the plunger includes a plunger rod, which (a) has a distal end portion to which the plunger head is coupled, and (b) is shaped so as to define an internal plunger space, and 
     wherein inserting the plunger head into the tubular container comprises inserting the plunger head into the tubular container while the collection vial is disposed at least partially within the internal plunger space. 
     Inventive Concept 339. The method according to Inventive Concept 338, wherein decoupling the collection vial from the plunger comprises removing the collection vial from the internal plunger space through a proximal opening of the internal plunger space.
 
Inventive Concept 340. The method according to Inventive Concept 338, wherein inserting the plunger head into the tubular container comprises inserting the plunger head into the tubular container while the collection vial is disposed partially within the internal plunger space, with an axial portion of the collection vial protruding proximally out of the proximal opening, the axial portion of the collection vial including an end of the collection vial opposite an end of the collection vial that defines the vial opening.
 
Inventive Concept 341. The method according to Inventive Concept 340, wherein the axial portion of the collection vial protrudes proximally out of the proximal opening by at least 4 cm.
 
Inventive Concept 342. The method according to Inventive Concept 340, wherein distally advancing the plunger head within the tubular container to drive the at least a portion of the liquid specimen sample through the filter comprises pushing on the axial portion of the collection vial.
 
Inventive Concept 343. The method according to Inventive Concept 333,
 
     wherein the plunger comprises a plunger rod, which has a distal end portion to which the plunger head is coupled, and 
     wherein inserting the plunger head into the tubular container comprises inserting the plunger head into the tubular container while the collection vial is disposed alongside the plunger rod. 
     Inventive Concept 344. The method according to any one of Inventive Concepts 316-323, 
     wherein advancing the filter into the collection vial via the plunger-head opening and the vial opening comprises axially moving a proximal portion of a shaft of the sampling device and the collection vial with respect to each other, such that (a) the proximal portion of the shaft moves through the plunger-head opening and the vial opening, and (a) a proximal end of the shaft pushes the filter through the plunger-head opening into the collection vial via the vial opening, and 
     wherein the proximal portion of the shaft is axially movable with respect to the proximal container opening. 
     Inventive Concept 345. The method according to Inventive Concept 344, wherein the sampling device is configured to automatically axially move the shaft through the filter-support shaft-passage region, the plunger-head opening, and the vial opening.
 
Inventive Concept 346. The method according to Inventive Concept 344, wherein the sampling device further comprises a spring, which is configured to axially move the proximal portion of the shaft with respect to the proximal container opening.
 
Inventive Concept 347. The method according to Inventive Concept 344,
 
     wherein placing the liquid specimen sample in the tubular container comprises placing the liquid specimen sample in the tubular container proximal to the filter that is disposed on a proximal support surface defined by a filter support that is disposed within the tubular container, and 
     wherein distally advancing the plunger head within the tubular container comprises distally advancing the plunger head within the tubular container to drive the at least a portion of the liquid specimen sample through the filter and a plurality of filtrate-passage openings defined by the filter support, 
     wherein the tubular container includes a distal tubular portion that is distal to the filter support and is configured to have an adjustable length, and 
     wherein axially moving the proximal portion of the shaft and the collection vial with respect to each other comprises shortening the adjustable length, so as to axially move the shaft through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     Inventive Concept 348. The method according to Inventive Concept 347, wherein shortening the adjustable length comprises axially collapsing the distal tubular portion.
 
Inventive Concept 349. The method according to any one of Inventive Concepts 316-323, further comprising sealing the vial opening with a collection vial cap after the filter has been advanced into the collection vial.
 
Inventive Concept 350. The method according to any one of Inventive Concepts 316-323, further comprising bathing the filter with a liquid within the collection vial when the filter is in the collection vial.
 
Inventive Concept 351. The method according to Inventive Concept 350, wherein the liquid is selected from the group consisting of: a lysis buffer, saline solution, and transport medium.
 
Inventive Concept 352. The method according to Inventive Concept 350, wherein the collection vial includes an internal chamber, which contains the liquid and is configured to prevent spillage of the liquid out of the collection vial regardless of an orientation of the collection vial.
 
Inventive Concept 353. The method according to Inventive Concept 352, further comprising, after the filter has been advanced into the collection vial, sealing the vial opening with a collection vial cap so as to automatically release the liquid from the internal chamber.
 
Inventive Concept 354. The method according to Inventive Concept 353, wherein the collection vial cap includes a shaft that extends from an inner surface of the collection vial cap, and is configured to puncture the internal chamber when the collection vial cap is placed on the vial opening.
 
Inventive Concept 355. The method according to any one of Inventive Concepts 316-323, further comprising, after the filter has been advanced into the collection vial, detecting the presence of a biological particulate trapped by the filter.
 
Inventive Concept 356. The method according to Inventive Concept 355, wherein detecting the presence of the biological particulate trapped by the filter comprising using a lateral flow immunoassay test strip to detect the presence of the biological particulate trapped by the filter.
 
Inventive Concept 357. The method according to Inventive Concept 355, wherein the biological particulate is selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen.
 
     The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A-G  are schematic illustrations of a sampling device for concentrating a liquid specimen sample, and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  2 A-G  are schematic cross-sectional illustrations of the sampling device of  FIGS.  1 A-G  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIG.  3    is an enlarged schematic illustration of the sampling device of  FIGS.  1 A-G  in the state shown in  FIGS.  1 C and  2 C , in accordance with an application of the present invention; 
         FIG.  4 A  is an enlarged schematic illustration of a portion of the sampling device of  FIGS.  1 A-G  in the state shown in  FIGS.  1 C and  2 C , in accordance with an application of the present invention; 
         FIG.  4 B  is an enlarged schematic illustration of an alternative configuration of a portion of the sampling device of  FIGS.  1 A-G  in the state shown in  FIGS.  1 C and  2 C , in accordance with an application of the present invention; 
         FIG.  5    is an enlarged schematic illustration of a plunger and a collection vial of the sampling device of  FIGS.  1 A-G  in the state shown in  FIGS.  1 A and  2 A , in accordance with an application of the present invention; 
         FIGS.  6 A-G  are schematic illustrations of another sampling device for concentrating a liquid specimen sample, and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  7 A-F  are schematic illustrations of yet another sampling device for concentrating a liquid specimen sample, and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  8 A-F  are schematic cross-sectional illustrations of the sampling device of  FIGS.  7 A-F  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  9 A-C  are schematic illustrations of portions of the sampling device of  FIGS.  7 A-F , in accordance with respective applications of the present invention; 
         FIGS.  10 A and  10 B  are schematic illustrations of another configuration of the sampling device of  FIGS.  1 A-G , in accordance with an application of the present invention; 
         FIG.  11    is a schematic illustration of a plunger fully inserted into a tubular container, in accordance with an application of the present invention; 
         FIG.  12    is a schematic illustration of another plunger fully inserted into another tubular container, in accordance with an application of the present invention; 
         FIGS.  13 A-D  are schematic illustrations of filters, in accordance with respective applications of the present invention; 
         FIGS.  14 A-B  are a schematic illustration and a schematic cross-sectional illustration of an alternative configuration of coupling between a filter support and a shaft, in accordance with an application of the present invention; 
         FIG.  15    is a schematic illustration of a testing kit, in accordance with an application of the present invention; 
         FIGS.  16 A-C  are schematic illustrations of another testing kit, in accordance with an application of the present invention; 
         FIG.  17    is a schematic illustration of yet another testing kit, in accordance with an application of the present invention; 
         FIGS.  18 A-G  are schematic illustrations of yet another sampling device for concentrating a liquid specimen sample, and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  19 A-G  are schematic cross-sectional illustrations of the sampling device of  FIGS.  18 A-G  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIG.  20    is an enlarged schematic illustration of the sampling device of  FIGS.  18 A-G  in the state shown in  FIGS.  18 E and  19 E , in accordance with an application of the present invention; 
         FIG.  21    is a schematic illustration of another configuration of the sampling device of  FIGS.  18 A-G  in the state shown in  FIGS.  18 E and  19 E , in accordance with an application of the present invention; 
         FIGS.  22 A-B  are schematic illustrations of another sampling device for concentrating a liquid specimen sample, and a portion of the sampling device, respectively, in accordance with an application of the present invention; 
         FIGS.  23 A-D  are schematic illustrations of the sampling device of  FIGS.  22 A-B  and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  24 A-D  are schematic cross-sectional illustrations of the sampling device of  FIGS.  22 A-B  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIG.  25    is an enlarged schematic illustration of a portion of the sampling device of  FIGS.  22 A-B  in the state shown in  FIGS.  23 D and  24 D , in accordance with an application of the present invention; 
         FIGS.  26 A-B  are schematic illustrations of yet another sampling device for concentrating a liquid specimen sample, and a portion of the sampling device, respectively, in accordance with an application of the present invention; 
         FIGS.  27 A-D  are schematic illustrations of the sampling device of  FIGS.  26 A-B  and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  28 A-D  are schematic cross-sectional illustrations of the sampling device of  FIGS.  26 A-B  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIG.  29    is an enlarged schematic illustration of a portion of the sampling device of  FIGS.  26 A-B  in the state shown in  FIGS.  27 D and  24 D , in accordance with an application of the present invention; 
         FIGS.  30 A-B  are schematic illustrations of a still another sampling device for concentrating a liquid specimen sample, and a portion of the sampling device, respectively, in accordance with an application of the present invention; 
         FIGS.  31 A-D  are schematic illustrations of the sampling device of  FIGS.  30 A-B  and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  32 A-D , which are schematic cross-sectional illustrations of the sampling device of  FIGS.  30 A-B  and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIG.  33    is an enlarged schematic illustration of a portion of the sampling device of  FIGS.  30 A-B  in the state shown in  FIGS.  31 D and  32 D , in accordance with an application of the present invention; 
         FIGS.  34 A-B  are schematic illustrations of a configuration of a portion of the sampling device of  FIGS.  26 A- 29   , in accordance with an application of the present invention; 
         FIGS.  35 A-B  are schematic cross-sectional illustrations of the portion of sampling device of  FIGS.  34 A-B , in accordance with an application of the present invention; 
         FIGS.  36 A-B  are schematic illustrations of another sampling device for concentrating a liquid specimen sample, and a portion of the sampling device, respectively, in accordance with an application of the present invention; 
         FIGS.  37 A-D  are schematic illustrations of the sampling device of  FIGS.  36 A-B  and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  38 A-D  are schematic cross-sectional illustrations of the sampling device of  FIGS.  36 A-B  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIG.  39    is an enlarged schematic illustration of a portion of the sampling device of  FIGS.  36 A-B  in the state shown in  FIGS.  37 D and  38 D , in accordance with an application of the present invention; 
         FIGS.  40 A-B  are schematic illustrations of yet another sampling device for concentrating a liquid specimen sample, and a portion of the sampling device, respectively, in accordance with an application of the present invention; 
         FIGS.  41 A-E  are schematic illustrations of the sampling device of  FIGS.  40 A-B  and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  42 A-E  are schematic cross-sectional illustrations of the sampling device of  FIGS.  40 A-B  and the method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  43 A-E  are schematic illustrations of still another sampling device and a method of using the sampling device, in accordance with respective applications of the present invention; 
         FIGS.  44 A-B  are schematic illustrations of a portion of another sampling device and a method of using the sampling device, in accordance with respective applications of the present invention; and 
         FIGS.  45 A-B  are schematic illustrations of a distal portion of a plunger head, in accordance with an application of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF APPLICATIONS 
     In some embodiments of the present invention, a sampling device  20  is provided for concentrating a liquid specimen sample  22 . 
     Reference is made to  FIGS.  1 A-G , which are schematic illustrations of a sampling device  120  for concentrating liquid specimen sample  22 , and a method of using sampling device  120 , in accordance with respective applications of the present invention. Sampling device  120  is one implementation of sampling device  20 . 
     Reference is also made to  FIGS.  2 A-G , which are schematic cross-sectional illustrations of sampling device  120  and the method of using sampling device  120 , in accordance with respective applications of the present invention. 
     Reference is further made to  FIG.  3   , which is an enlarged schematic illustration of sampling device  120  in the state shown in  FIGS.  1 C and  2 C , in accordance with an application of the present invention. 
     Reference is still further made to  FIG.  4 A , which is an enlarged schematic illustration of a portion of sampling device  120  in the state shown in  FIGS.  1 C and  2 C , in accordance with an application of the present invention. 
     Reference is still further made to  FIG.  4 B , which is an enlarged schematic illustration of an alternative configuration of a portion of sampling device  120  in the state shown in  FIGS.  1 C and  2 C , in accordance with an application of the present invention. 
     Reference is still further made to  FIG.  5   , which is an enlarged schematic illustration of a plunger  40  and a collection vial  50  of sampling device  120  in the state shown in  FIGS.  1 A and  2 A , in accordance with an application of the present invention. 
     Reference is additionally made to  FIGS.  6 A-G , which are schematic illustrations of a sampling device  220  for concentrating liquid specimen sample  22 , and a method of using sampling device  220 , in accordance with respective applications of the present invention. Sampling device  220  is one implementation of sampling device  20 . 
     Reference is yet additionally made to  FIGS.  7 A-F , which are schematic illustrations of a sampling device  320  for concentrating liquid specimen sample  22 , and a method of using sampling device  320 , in accordance with respective applications of the present invention. Sampling device  320  is one implementation of sampling device  20 . 
     Reference is also made to  FIGS.  8 A-F , which are schematic cross-sectional illustrations of sampling device  320  and the method of using sampling device  320 , in accordance with respective applications of the present invention. 
     Reference is further made to  FIGS.  9 A-C , which are schematic illustrations of portions of sampling device  320 , in accordance with respective applications of the present invention. 
     All references herein to sampling device  20  are to be understood as referring to sampling devices  120 ,  220 , and  320 , and like parts have like reference numerals. 
     Sampling device  20  comprises a filtration assembly  24  and collection vial  50 . Filtration assembly  24  comprises a tubular container  30  and plunger  40 . Tubular container  30  is shaped so as to define a proximal container opening  32  for receiving liquid specimen sample  22 . Optionally, proximal container opening  32  has a conical or funnel shape to facilitate receipt of liquid specimen sample  22 , which may, for example, be expressed (e.g., spit) from subject&#39;s mouth into tubular container  30 , or transferred to tubular container  30  from a collection container. Optionally, the funnel shape of proximal container opening  32  is similar to funnel-shaped proximal opening  36  shown in FIG. 1 of US Patent Application Publication 2019/0381498 to Fruchter et al., which is incorporated herein by reference. Tubular container may be cylindrical, as shown, or may alternatively have another, non-circular cross-sectional shape. Alternatively or additionally, tubular container  30  may have different cross-sectional shapes along respective different longitudinal portions of the tubular container; optionally, one or more of the cross-sectional shapes is circular. Tubular container  30  is also shaped so as to define an inner wall  34 . At least a portion of tubular container  30 , such as a proximal portion, may define a syringe barrel. 
     Typically, tubular container  30  has an internal volume of at least 0.5 ml (e.g., at least 1 ml, such as at least 5 ml), no more than 500 ml (e.g., no more than 70 ml), and/or between 0.5 ml (e.g., 1 ml or 5 ml) and 500 ml (e.g., 70 ml). 
     For some applications, tubular container  30  does not comprise a Luer lock or any other type of needle-coupling mechanism. 
     For some applications, collection vial  50  has a volume of at least 1 ml, no more than 50 ml, and/or between 1 and 50 ml, such as at least 2 ml, no more than 20 ml, and/or between 2 and 20 ml, e.g., at least 3 ml (e.g., at least 5 ml), no more than 15 ml, and/or between 3 (e.g., 5) and 15 ml. For some applications, collection vial  50  has a greatest internal diameter of no more than 35 mm, e.g., no more than 20 mm, such as no more than 15 mm or no more than 10 mm. 
     Collection vial  50  is typically shaped so as to define a vial opening  52 . 
     For some applications, collection vial  50  is tapered toward an end  89  of collection vial  50  opposite an end  91  of collection vial  50  that defines vial opening  52  (labeled in  FIG.  3   ). For example, the collection vial may include a frustoconical tapered portion at end  89 . 
     Collection vial  50  has a greatest outer diameter D 1  (labeled in  FIG.  3   ) that is less than (e.g., less than 80%, such as less than 70%) an inner diameter D 2  (labeled in  FIG.  3   ) of an axial portion of tubular container  30  in which plunger head  42  is distally advanceable. 
     Plunger  40  comprises a plunger head  42 , which is shaped so as to define a plunger-head opening  44  through plunger head  42 . Plunger  40  is insertable into tubular container  30  via proximal container opening  32 , such that a lateral surface  46  of plunger head  42  (labeled in  FIGS.  3 ,  4 A, and  5   ) forms a fluid-tight movable seal with inner wall  34 . To this end, lateral surface  46  may comprise an elastomeric material, such as natural rubber, synthetic rubber, a thermoplastic elastomer, or a combination thereof. 
     For some applications, such as shown in  FIGS.  1 A- 9 B  and labeled in  FIGS.  3 ,  5 ,  9 A , and  9 C, plunger  40  comprises a plunger rod  82 , which has a distal end portion  84  to which plunger head  42  is coupled. In sampling devices  120  and  220 , plunger  40  is a plunger  140 , plunger head  42  is a plunger head  142 , plunger rod  82  is a plunger rod  182 , and distal end portion  84  is a distal end portion  184  to which plunger head  142  is coupled, optionally disengageably coupled, such as described hereinbelow with reference to  FIGS.  1 D-E ,  2 D-E, and  6 D-E. In sampling device  320 , plunger  40  is a plunger  340 , plunger head  42  is a plunger head  342 , plunger rod  82  is a plunger rod  382 , and distal end portion  84  is a distal end portion  384  (labeled in  FIG.  9 A ) to which plunger head  342  is coupled, optionally fixedly coupled, such as described hereinbelow with reference to  FIGS.  7 C-D  and  8 C-D and labeled in  FIGS.  9 A and  9 C . References hereinbelow to plunger  40 , plunger head  42 , plunger rod  82 , and distal end portion  84  are to be understood as including plungers  140  and  340 , plunger heads  142  and  342 , plunger rods  182  and  382 , and distal end portions  184  and  384 , respectively, unless otherwise indicated. 
     For some applications, a cross-sectional area of plunger-head opening  44  is at 20%, no more than 90%, and/or between 20% and 90% of a cross-sectional area of a distal surface of plunger head  42  (the cross-sectional area of the distal surface including the cross-sectional area of plunger-head opening  44 ). 
     When sampling device  20  is in its initial state (which is typically set during manufacture thereof), as shown in  FIGS.  1 A,  2 A,  5 ,  6 A,  7 A,  8 A,  9 A, and  9 C , collection vial  50  is positioned proximal to plunger head  42 . 
     Typically, filtration assembly  24  further comprises a filter  60 . Filter  60  is configured to concentrate at least a portion of liquid specimen sample  22  onto filter  60 , while allowing a filtrate  61  to pass through filter  60 . Typically, distal advancement of plunger  40  within tubular container  30  applies pressure to drive (e.g., push) at least a portion of liquid specimen sample  22  contained in tubular container  30  through filter  60 , such as shown in the transitions between  FIGS.  1 B and  1 C , between  FIGS.  2 B and  2 C , between  FIGS.  6 B and  6 C , between  FIGS.  7 A and  7 B , and between  FIGS.  8 A and  8 B . Typically, filtration assembly  24  is configured such that when plunger head  42  is within tubular container  30 , fluid communication is blocked between (a) tubular container  30  distal to plunger head  42  and (b) proximal container opening  32 . 
     Filter  60  comprises synthetic or natural materials formed, for example, as a matrix, membrane, fabric, beads, or other configuration. For some applications, filter  60  comprises a mechanical filter, which is configured to mechanically filter particulate from liquid specimen sample  22  by size-based filtration. Optionally, filter  60  comprises a depth filter. 
     Alternatively or additionally, for some applications, filter  60  comprises fixed antibodies configured to capture the particulate (e.g., free viral particles) by affinity-based filtration. 
     For some applications, for example, when filter  60  is used for capturing free virus, virions, or viral particles by size-based filtration, filter  60  may have a pore size of between 0.01 and 0.3 microns and/or a molecular weight cut off of between 10 kDa and 500 kDa. For some applications, filter  60  has a pore size of between 0.2 and 2.0 microns, for example, when filter  60  is used for capturing bacteria by size-based filtration. 
     For other applications, filter  60  has a nominal pore size of between 30 microns and 1.5 mm, the nominal pore size representative of a minimum size of spherical particles necessary for the filter to retain 85% of the spherical particles when H2O containing the spherical particles is passed through the filter at 20 degrees C. under pressure supplied by a 10 cm water column. For these applications, filter  60  may implement techniques described in U.S. Provisional Application 63/117,294, filed Nov. 23, 2020, is assigned to the assignee of the present application and incorporated herein by reference. 
     For example, the nominal pore size may be at least 40 microns, such as at least 60 microns, e.g., at least 100 microns, at least 120 microns, at least 150 microns, at least 200 microns, or at least 500 microns. Alternatively or additionally, for example, the nominal pore size may be less than 1 mm, such as less than 750 microns, less than 500 microns, or less than 250 microns. 
     For some applications, filtration assembly  24  comprises a plurality of filters, such as described hereinbelow with reference to  FIGS.  10 A-B . Optionally, two or more of the plurality of filters touch one another, such as shown in  FIGS.  10 A-B , or are separated by one another by one or more thin spacers, e.g., having a thickness of at least 0.05 mm, no more than 1 mm, and/or between 0.05 and 1 mm (configuration not shown). Alternatively or additionally, two or more of the plurality of filters are spaced apart from another, which case filtration assembly  24  optionally comprises a corresponding number of filter supports, some or all of which may have some or all of the characteristics of filter support  62  (configuration not shown). Further alternatively or additionally, filtration assembly  24  comprises one or more additional filters downstream of filter  60  (configuration not shown). 
     Typically, filtration assembly  24  further comprises a waste liquid receptacle  56  for receiving filtrate  61 . For some applications, a distal portion of tubular container  30  is shaped so as to define waste liquid receptacle  56 , such as shown in the drawings. For other applications, waste liquid receptacle  56  is provided as a separate container coupled in fluid communication with tubular container  30  downstream (distally) to filter  60  (configuration not shown). 
     Optionally, waste liquid receptacle  56  is shaped so as to define an opening  58  through an external wall of waste liquid receptacle  56  to release displaced air. For example, opening  58  may be located on a side portion of the external wall, typically above the highest level that filtrate  61  is expected to reach during ordinary use of the device. For some applications, waste liquid receptacle  56  comprises an air filter (e.g., an N98 filter) that is disposed to filter air that passes out of waste liquid receptacle  56  through opening  58  (not shown). Alternatively or additionally, for some applications, waste liquid receptacle  56  comprises a one-way pressure-sensitive valve disposed in opening  58 . 
     For some applications, waste liquid receptacle  56  contains a disinfectant or a liquid-absorbing material. 
     Reference is made to  FIGS.  1 A-G ,  2 A-G,  3 - 5 ,  7 A-F, and  8 A-F. For some applications, such as shown in  FIGS.  1 B-C  and  2 B-C for sampling device  120 , and in  FIGS.  7 A-B  and  8 A-B for sampling device  320 , during the above-mentioned distal advancement of plunger  40  within tubular container  30 , collection vial  50  is positioned proximal to plunger head  42  such that vial opening  52  of collection vial  50  is in fluid communication with plunger-head opening  44 . Collection vial  50  is configured to prevent escape of air from collection vial  50  as pressure builds up in collection vial  50  during distal advancement of plunger head  42  in tubular container  30  while sampling device  120  or  320  is oriented such that proximal container opening  32  faces upward away from the Earth. The air pressure builds up in collection vial  50  because of an air pocket trapped in collection vial  50  during distal advancement of plunger  40  within tubular container  30  inhibits fluid flow into collection vial  50  during distal advancement of plunger  40 . Collection vial  50  typically is not shaped so as to define any pressure-release openings and does not comprise any pressure-release valves. 
     Reference is again made to  FIGS.  1 A- 9 B . For some applications, filter  60  is disposed within tubular container  30 . For some of these applications, plunger  40  is insertable into tubular container  30  from outside tubular container  30  via proximal container opening  32  while filter  60  is disposed within tubular container  30 . In other words, filter  60  is not coupled to plunger head  42 , at least before insertion of plunger  40  into tubular container  30  (although filter  60  may become coupled to plunger head  42  during a portion of the use of sampling device  20 ). For other applications, filter  60  is coupled to the plunger head, such as described hereinbelow with reference to  FIGS.  22 A- 25 ,  26 A- 29 ,  30 A- 33 ,  34 A- 35 B,  36 A- 39 ,  40 A- 42 E,  43 A -E,  44 A-B, and  45 A-B. 
     For some applications, sampling device  20  is configured such that filter  60  is advanceable into collection vial  50  via vial opening  52  while collection vial  50  is disengageably coupled to filtration assembly  24 . 
     For some applications, filtration assembly  24  is configured such that movement (such as distal advancement) of plunger head  42  and collection vial  50  within tubular container  30  advances filter  60  into (such as entirely into) collection vial  50  via plunger-head opening  44  and vial opening  52 , for example, such as described hereinbelow with reference to  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     Reference is made to  FIGS.  1 A,  2 A,  3 - 5 ,  7 A, and  8 A . For some applications, such as shown in  FIGS.  1 A,  2 A, and  3 - 5    for sampling device  120 , and in  FIGS.  7 A and  8 A  for sampling device  320 , vial opening  52  of collection vial  50  is in fluid communication with plunger-head opening  44  (typically including when sampling device  120  or  320  is in its initial state, which is typically set during manufacture thereof). 
     Reference is made to  FIGS.  6 A-G . For some applications, such as shown in these figures for sampling device  220 , sampling device  220  further comprises a fluid-tight frangible seal  276  when sampling device  220  is in its initial state, which is typically set during manufacture thereof). Collection vial  50  is disengageably coupled to plunger  40  and positioned proximal to plunger head  42  such that frangible seal  276  removably blocks liquid flow from plunger-head opening  44  into vial opening  52  of collection vial  50 , such that upon breaching of frangible seal  276 , such as shown in  FIG.  6 D , vial opening  52  is in fluid communication with plunger-head opening  44 . Sampling device  320 , described herein with reference to  FIGS.  7 A-F ,  8 A-F, and  9 A-C, may also comprise frangible seal  276 , mutatis mutandis (configuration not shown). 
     Frangible seal  276  may be coupled to plunger-head opening  44  (such as shown), plunger head  42  (configuration not shown), vial opening  52  (configuration not shown), another element disposed between plunger-head opening  44  and vial opening  52  (configuration not shown), or a combination of these locations. 
     For example, frangible seal  276  may comprise a pliable material (such as silicone) that is easily torn or a rigid material that is easily broken (e.g., shaped so as define slits to aid in breaking). 
     Reference is again made to  FIGS.  1 A-G ,  2 A-G,  3 - 5 ,  6 A-G,  7 A-F, and  8 A-F. For some applications, filtration assembly  24  further comprises a filter support  62 , which is disposed within tubular container  30 . Filter support  62  is shaped so as to define:
         a proximal support surface  64 , which may be perpendicular to a central longitudinal axis  66  of tubular container  30  (as shown), or may be angled with respect to central longitudinal axis  66  (configuration not shown), and   a plurality of filtrate-passage openings  68  through filter support  62 .       

     Filter  60  is disposed on proximal support surface  64 . 
     For some of these applications, filter support  62  is shaped so as to further define a filter-support shaft-passage region  69 , which, for some applications, is shaped so as to define a filter-support opening  70  through filter support  62 . For these applications, filtration assembly  24  further comprises a shaft  72 . Plunger head  42 , filter support  62 , and shaft  72  are configured such that a proximal portion  74  of shaft  72  (labeled in  FIGS.  2 D-F ,  6 D-F, and  8 C-E) is axially movable through filter-support shaft-passage region  69  (e.g., filter-support opening  70 ), plunger-head opening  44 , and vial opening  52 , as shown in the transition between  FIG.  2 C  and  FIG.  2 E , between  FIG.  6 C  and  FIG.  6 E , and between  FIG.  8 B  and  FIG.  8 D . 
     For other applications, such as shown in  FIG.  4 B , filter-support shaft-passage region  69  is at least partially frangible, and filter support  62  and shaft  72  are configured such that axial movement of proximal portion  74  of shaft  72  through filter-support shaft-passage region  69  forms filter-support opening  70  through filter support  62 . After formation of filter-support opening  70 , proximal portion  74  of shaft  72  (labeled in  FIGS.  2 D-F ,  6 D-F, and  8 C-E) is axially movable through filter-support opening  70 , plunger-head opening  44 , and vial opening  52 . Typically, pressure generated in liquid specimen sample  22  by distal advancement of plunger  40  within tubular container  30  is not sufficient to break filter-support shaft-passage region  69  and prematurely form filter-support opening  70 . 
     For some applications, filter-support shaft-passage region  69  is integral with other portions (e.g., other more peripheral portions) of filter support  62  and is thinner than the other portions of filter support  62  (such as shown). Alternatively, for some applications, filter-support shaft-passage region  69  comprises a frangible membrane (configuration not shown). 
     Reference is again made to  FIGS.  1 A-G ,  2 A-G,  3 - 5 ,  6 A-G,  7 A-F, and  8 A-F. Shaft  72  may be cylindrical, as shown, or may alternatively have another, non-circular cross-sectional shape, such as a polygonal shape (e.g., a rectangular, square, or triangular shape), an “x” shape, or an asterisk shape. Alternatively or additionally, shaft  72  may have different cross-sectional shapes along respective different longitudinal portions of the tubular container; optionally, one or more of the cross-sectional shapes is circular. Optionally, filter-support shaft-passage region  69  (e.g., filter-support opening  70 ) may have a shape corresponding to the shape of shaft  72 . 
     Typically, a cross-sectional area of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ) is substantially larger than an average cross-sectional area of filtrate-passage openings  68 ; for example, the cross-sectional area of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ) may be at least 10 times, such as at least 25 times, the average cross-sectional area of filtrate-passage openings  68 . 
     For some applications:
         the cross-sectional area of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ) is between 20 and 75 mm2,   the average cross-sectional area of filtrate-passage openings  68  is between 0.5 and 1.5 mm2,   the cross-sectional area of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ) is between 2.5% and 20% of a cross-sectional area of proximal support surface  64  of filter support  62 .       

     For some of these applications, proximal portion  74  of shaft  72 , filter-support shaft-passage region  69  (e.g., filter-support opening  70 ), plunger-head opening  44 , and vial opening  52  are coaxial. Alternatively or additionally, for some of these applications, proximal portion  74  of shaft  72 , filter-support shaft-passage region  69  (e.g., filter-support opening  70 ), plunger-head opening  44 , and vial opening  52  are coaxial with or parallel to central longitudinal axis  66  of tubular container  30 . 
     For some applications, a cross-sectional area of proximal portion  74  of shaft  72  is between 80% and 110% of a cross-sectional area of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ). 
     For some of these applications in which filter-support shaft-passage region  69  is shaped so as to define filter-support opening  70 , when sampling device  20  is in its initial state (which is typically set during manufacture thereof), as shown in  FIGS.  1 A,  2 A,  6 A,  7 A , and  8 A, a proximal end  75  (labeled in  FIGS.  3  and  4 A ) of proximal portion  74  of shaft  72  is positioned:
         protruding proximally from support surface  64  of filter support  62 , typically slightly (e.g., no more than 3 mm (such as shown in as shown in  FIGS.  1 A,  2 A,  6 A,  7 A, and  8 A ),   within filter-support opening  70  (configuration not shown),   flush with proximal support surface  64  of filter support  62  (configuration not shown), or   distal to filter-support opening  70  (configuration not shown).       

     For some applications, such as shown, for example, in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D, sampling device  20  is configured such that movement (e.g., distal advancement) of plunger head  42  and collection vial  50  within tubular container  30  advances filter  60  into (typically entirely into) collection vial  50  via plunger-head opening  44  and vial opening  52 . 
     For some of these applications, sampling device  20  is configured such that the movement of plunger head  42  and collection vial  50  within tubular container  30  advances filter  60  into collection vial  50  via plunger-head opening  44  and vial opening  52  while filter  60  remains stationary with respect to a distal end of tubular container  30 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     Alternatively or additionally, proximal withdrawal of plunger  40  within and/or out of tubular container  30 , or a combination of distal advancement and proximal withdrawal of plunger  40 , advances filter  60  into (typically entirely into) collection vial  50  via plunger-head opening  44  and vial opening  52  (configurations not shown). 
     For some applications in which sampling device  20  is configured such that movement of plunger head  42  and collection vial  50  within tubular container  30  advances filter  60  into collection vial  50 , relative axial movement between shaft  72  and collection vial  50  causes proximal portion  74  of shaft  72  to push filter  60  into collection vial  50  via vial opening  52 , such as shown in  FIGS.  1 D,  2 D,  6 D,  7 C, and  8 C . In sampling device  220 , advancing proximal portion  74  of shaft  72  into collection vial  50  breaches frangible seal  276  such that vial opening  52  is in fluid communication with plunger-head opening  44 , such as shown in  FIG.  6 D . 
     As mentioned above, typically first distal advancement of plunger  40  within tubular container  30  applies pressure to drive (e.g., push) at least a portion of liquid specimen sample  22  contained in tubular container  30  through filter  60 , without pushing filter support  62  distally within tubular container  30 , such as shown in the transitions between  FIGS.  1 B and  1 C , between  FIGS.  2 B and  2 C , between  FIGS.  6 B and  6 C , between  FIGS.  7 A and  7 B , and between  FIGS.  8 A and  8 B . For some applications, after this first distal advancement of plunger  40  within tubular container  30 , further second distal advancement of plunger head  42  directly or indirectly pushes filter support  62  distally within tubular container  30 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. During this further second distal advancement, proximal portion  74  of shaft  72  remains axially stationary with respect to collection vial  50 . For these applications, filter support  62  is slidable along tubular container  30 , and proximal portion  74  of shaft  72  is axially fixed with respect to proximal container opening  32  of tubular container  30 . 
     As a result of this relative axial movement between shaft  72  and collection vial  50 , proximal portion  74  of shaft  72  axially moves through filter-support shaft-passage region  69  (e.g., filter-support opening  70 ), plunger-head opening  44 , and vial opening  52 , into collection vial  50 , as shown in  FIGS.  1 D,  2 D,  6 D,  7 C, and  8 C . During this movement, proximal portion  74  of shaft  72  engages filter  60  and pushes the filter into collection vial  50 , as shown in  FIGS.  1 D,  2 D,  6 D,  7 C, and  8 C . Typically, additional distal advancement of plunger  40  within tubular container  30  pushes filter  60  entirely into collection vial  50 , as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     In these applications, a lateral surface  63  (labeled in  FIGS.  3  and  4 A ) of filter support  62  is typically configured to form a fluid-tight movable seal with inner wall  34  of tubular container  30 . 
     For some applications, sampling device  20  is configured such that the further second distal advancement of plunger head  42 , described hereinabove with reference to  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D, pushes filter support  62  distally within tubular container  30  with respect to shaft  72 , such that proximal portion  74  of shaft  72  pushes filter  60  through filter-support shaft-passage region  69 , plunger-head opening  44 , and vial opening  52 , into collection vial  50 . 
     For some applications, filter support  62  and shaft  72  are releasably coupled to each other such that:
         the first distal advancement of plunger head  42  within tubular container  30 , described hereinabove with reference to the transitions between  FIGS.  1 B and  1 C , between  FIGS.  2 B and  2 C , between  FIGS.  6 B and  6 C , between  FIGS.  7 A and  7 B , and between  FIGS.  8 A and  8 B , does not decouple filter support  62  from shaft  72 , and   the further second distal advancement of plunger head  42 , described hereinabove with reference to  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D, decouples filter support  62  from shaft  72 .       

     For example, such as shown in  FIG.  4 A , proximal portion  74  of shaft  72  may be releasably coupled to filter support  62  by one or more frangible portions  73  of filtration assembly  24 , such as of filter support  62  (as shown) or proximal portion  74  of shaft  72  (configuration not shown). Proximal portion  74  of shaft  72  may be positioned within filter-support opening  70 , releasably coupled to filter support  62  by the one or more frangible portions  73 . 
     For example, frangible portions  73  may be shaped as a plurality of tabs distributed around the perimeter of proximal portion  74  of shaft  72 . Optionally, proximal portion  74  of shaft  72 , filter-support opening  70 , and the tabs are shaped so as to define a plurality of narrow spaces between proximal portion  74  of shaft  72  and the perimeter of filter-support opening  70 ; these narrow spaces may serve to allow passage of liquid specimen sample  22  through filter support  62 , and thus serve the same function as filtrate-passage openings  68 . 
     For some applications, sampling device  20  is configured such that the further second distal advancement of plunger head  42 , described hereinabove with reference to  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D, pushes filter support  62  distally within tubular container  30  in the absence of a filter-support release action by a user. The user merely distally advances plunger head  42  within tubular container  30 , and need not be aware of the transition between the first distal advancement and the subsequent further second distal advancement (although the user may feel an increase in resistance during the transition). 
     For other applications, filter support  62  and shaft  72  are releasably axially locked with respect to each other, and sampling device  20  is configured such that a filter-support release action by a user unlocks filter support  62  and shaft  72  from each other. For example, proximal portion  74  of shaft  72  may have a non-circular shape (e.g., a triangular shape), and the filter-support release action is rotation, by the user, of filter support  62  with respect to shaft  72 , in order to align the shape of proximal portion  74  of shaft  72  with a corresponding shape of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ). 
     For some applications, such as shown in  FIGS.  1 F,  2 F,  6 F,  7 E, and  8 E , collection vial  50  is disengageably coupled to plunger  40 . Such as described hereinbelow, once collection vial  50  has been removed from plunger  40 , a diagnostic test may be performed for the presence of particulate trapped by filter  60 , which is now in collection vial  50 . For some applications, such as for transporting collection vial  50  to a remote diagnostic laboratory, sampling device  20  further comprises a collection vial cap  80 , which is configured to seal vial opening  52 , such as shown in  FIGS.  1 G,  2 G,  6 G,  7 F, and  8 F . 
     For some applications, such as shown in  FIGS.  1 F,  2 F,  6 F,  7 E, and  8 E , sampling device  20  is configured such that collection vial  50  is decouplable from plunger  40  while plunger head  42  is within tubular container  30 , typically, but not necessarily, via a proximal end  81  of plunger  40 . For some of these applications, sampling device  20  is configured such that collection vial  50  is decouplable from plunger  40  while plunger head  42  is advanced as far as possible within tubular container  30 . Alternatively or additionally, for some of these applications, sampling device  20  is configured such that collection vial  50  is decouplable from plunger  40  without any proximal withdrawal of plunger head  42  within tubular container  30 . 
     For some applications in which plunger  40  comprises plunger rod  82 , plunger rod  82  is shaped so as to define an internal plunger space  86  (labeled in  FIGS.  3  and  5   ), and collection vial  50  is removably disposed at least partially within internal plunger space  86 , such as shown in  FIGS.  1 A-E ,  2 A-E,  3 ,  4 A,  5 ,  6 A-E,  7 A-D,  8 A-D, and  9 A-C. For some of these applications, a proximal end  88  of plunger rod  82  is shaped so as to define a plunger-space proximal opening  90  of internal plunger space  86 . In sampling devices  120  and  220 , internal plunger space  86  is an internal plunger space  186 , proximal end  88  of plunger rod  82  is a proximal end  188  of plunger rod  182 , and plunger-space proximal opening  90  is a plunger-space proximal opening  190  (labeled in  FIGS.  3  and  5   ); in sampling device  320 , internal plunger space  86  is an internal plunger space  386  (labeled in  FIGS.  8 A,  8 E, and  9 A ), proximal end  88  of plunger rod  82  is a proximal end  388  (labeled in  FIGS.  9 A-B ) of plunger rod  382 , and plunger-space proximal opening  90  is a plunger-space proximal opening  390  (labeled in  FIG.  9 A ). References hereinbelow to internal plunger space  86 , proximal end  88 , and plunger-space proximal opening  90  are to be understood as including internal plunger spaces  186  and  386 , proximal ends  188  and  388 , and plunger-space proximal openings  190  and  390 , respectively, unless otherwise indicated. 
     For some applications, the sampling device is configured such that collection vial  50  is removable from internal plunger space  86  through plunger-space proximal opening  90 , optionally while plunger head  42  is within tubular container  30  (collection vial  50  is also removable from internal plunger space  86  through plunger-space proximal opening  90  if plunger head  42  has been removed from tubular container  30 ). 
     Alternatively or additionally, the sampling device is configured such that filter  60  is removable from tubular container  30  (and from filtration assembly  24 ) via plunger-space proximal opening  90 , optionally while plunger head  42  is within tubular container  30 . In some configurations, such as described with reference to  FIGS.  1 A-E ,  2 A-E,  3 ,  4 A,  5 ,  6 A-E,  7 A-D,  8 A-D, and  9 A-C, filter  60  is within collection vial  50  when filter  60  is removable from tubular container  30  (and from filtration assembly  24 ) via plunger-space proximal opening  90 , optionally while plunger head  42  is within tubular container  30 . 
     For some applications, collection vial  50  is disengageably coupled axially with respect to plunger  40 , such as shown in  FIGS.  1 A-C ,  2 A-C,  3 ,  5 ,  6 A-C,  7 A-C, and  8 A-C. In other words, when coupled with respect to plunger  40 , collection vial  50  remains axially stationary with respect to plunger  40 , and thus advances distally to the same extent as plunger  40 , as can be seen in the transition from  FIGS.  1 A to  1 C  and from  FIGS.  2 A to  2 C ; the transition from  FIGS.  6 A to  6 C ; and the transition from  FIGS.  7 A to  7 C  and from  FIGS.  8 A to  8 C . 
     Collection vial  50  is configured to become disengaged from plunger  40  in order to allow collection vial  50  to be removed from plunger  40  (such as from internal plunger space  86  through plunger-space proximal opening  90 ), such as shown in  FIGS.  1 F,  2 F,  6 F,  7 E, and  8 E . 
     For applications in which pushing on axial portion  87  of collection vial  50  distally advances plunger head  42  while plunger rod  82  remains stationary with respect to tubular container  30 , such as described hereinbelow and shown in  FIGS.  2 D-E  and  6 D-E, the distal advancement of collection vial  50  shown in  FIGS.  2 D-E  and  6 D-E disengages collection vial  50  from plunger  40 . For some of these applications, such as shown in  FIGS.  2 A-G ,  3 ,  5 , and  6 A-G, sampling device  120  and  220  comprises one or more couplers  154 , which are configured to disengageably couple an external surface of collection vial  50  axially with respect to an internal surface of internal plunger space  186 , such as shown in  FIGS.  1 A-C ,  2 A-C,  3 ,  5 ,  6 A-C,  7 A-C, and  8 A-C. Typically, the one or more couplers  154  are disengageably coupled to the external surface of collection vial  50  at least partially by friction, and, optionally, additionally by slight penetration of respective sharp portions of the one or more couplers  154  into the external surface of collection vial  50 . 
     Optionally, the one or more couplers  154 , upon becoming fully disengaged from collection vial  50  and the internal surface of internal plunger space  186 , fall out of internal plunger space  186 , typically into tubular container  30 , such as shown in  FIGS.  2 E-F  and  6 E-F. 
     For other applications, such as shown in  FIGS.  7 A-F ,  8 A-F, and  9 A-C, sampling device  320  comprises one or more couplers  354 , which are configured to disengageably couple an external surface of collection vial  50  axially with respect to a proximal portion of plunger rod  382 , such as a proximal end  388  of plunger rod  382 , as shown. For example, the one or more couplers  354  may be configured to disengageably couple the external surface of collection vial  50  axially with respect to a flange  378  defined by the proximal portion of plunger rod  382 , such as by proximal end  388  of plunger rod  382 , as shown. For example, each of the one or more couplers  354  may be shaped so as to define proximal and distal graspers  379 A and  379 B that engage proximal and distal surfaces, respectively, of flange  378 , thereby sandwiching a portion  383  (labeled in  FIG.  9 B ) of flange  378  between proximal and distal graspers  379 A and  379 B in a slot  385  (labeled in  FIG.  9 B ) defined by the coupler between proximal and distal graspers  379 A and  379 B. Optionally, portion  383  is indented, as shown. 
     Typically, the one or more couplers  354  are disengageably coupled to the external surface of collection vial  50  at least partially by friction, and, optionally, additionally by slight penetration of respective sharp portions of the one or more couplers  354  into the external surface of collection vial  50 . 
     For some applications, such as shown in the transition between  FIGS.  7 B and  7 C  and between  FIGS.  8 B and  8 C , distal advancement of plunger rod  382  within tubular container  30 , such as until flange  378  prevents further distal advancement of plunger rod  382 , causes the one or more couplers  354  to at least partially disengage from flange  378 , so as to allow proximal withdrawal of collection vial  50  from plunger rod  382 , typically by proximally withdrawing the one or more couplers  354 , such as shown in the transition between  FIGS.  7 C and  7 D  and between  FIGS.  8 C and  8 D . Optionally, the one or more respective proximal graspers  379 A may continue to engage the proximal surface of flange  378 , such as shown. Optionally, the one or more couplers  354  at least partially disengage from flange  378  by pivoting of respective portions of the one or more couplers  354  with respect to flange  378 , such as shown. 
     For some applications, the one or more couplers  354  are configured to continue to engage collection vial  50  even after the one or more couplers entirely disengage from plunger rod  382 , such as shown in  FIGS.  7 D and  8 D . 
     For some applications in which the one or more couplers  354  comprise two or more couplers  354  (e.g., exactly two couplers  354 , as shown), sampling device  320  further comprises a proximal grip  392 . The two or more couplers  354  are fixed to and extend distally from proximal grip  392 . 
     For some applications, such as shown in  FIGS.  7 A-F ,  8 A-F, and  9 A-C, tubular container  30  comprises one or more proximal clips  394 , which are configured to engage flange  378  (such as by snapping onto flange  378 ) upon maximal distal advancement of plunger  340  within tubular container  30 , such as shown in  FIGS.  7 C,  8 C, and  9 B . 
     For some applications, an external surface of plunger rod  382  is shaped so as to define a plurality of protrusions  396  arranged along plunger rod  382 , which are configured to engage inner wall  34  of tubular container  30 . Protrusions  396  may slow down distal advancement of plunger rod  382  in tubular container  30 , such as to provide uniform speed of advancement and controlled buildup of pressure and filtration in tubular container  30 , which may aid in calibration of sampling device  320  during manufacture. Alternatively or additionally, protrusions  396  may provide an indication to the user of the speed and/or amount of distal advancement of plunger rod  382  in tubular container  30 . 
     For some applications, collection vial  50  is disposed alongside plunger rod  82  (configuration not shown). 
     For some applications, sterile packaging is provided, in which at least sampling device  20  is removably disposed. 
     Reference is again made to  FIGS.  1 A-G ,  2 A-G,  6 A-G,  7 A-F, and  8 A-F. In some applications of the present invention, a method for concentrating liquid specimen sample  22  is provided, the method comprising:
         placing liquid specimen sample  22  in tubular container  30  of filtration assembly  24 , optionally proximal to filter  60  that is disposed within tubular container  30 , such as shown in  FIGS.  1 A,  2 A,  6 A,  7 A, and  8 A ;   inserting plunger head  42  of plunger  40  into tubular container  30  via proximal container opening  32  of tubular container  30 , while collection vial  50  is positioned proximal to plunger head  42 , such that lateral surface  46  of plunger head  42  forms a fluid-tight movable seal with inner wall  34  of tubular container  30 , such as shown in  FIGS.  1 B,  2 B,  6 B,  7 B, and  8 B ;   distally advancing plunger head  42  within tubular container  30  to drive at least a portion of liquid specimen sample  22  through filter  60 , such as shown in  FIGS.  1 C,  2 C,  6 C,  7 B, and  8 B ; and   advancing filter  60  into (such as entirely into) collection vial  50  via plunger-head opening  44  and vial opening  52  of collection vial  50 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D.       

     For some applications, liquid specimen sample  22  is received from a subject&#39;s mouth. For some applications, liquid specimen sample  22  comprises gargled fluid, i.e., a gargle fluid that the subject has gargled in his or her mouth and spit out, perhaps along with some saliva. In the present application, including in the claims, “gargled fluid” means “gargle fluid” that has been gargled by a subject. Typically, the gargle fluid includes water, carbonated water, saline (e.g., phosphate buffered saline), pelargonium sidoides extract, tannic acid, balloon flower platycodon  grandiflorus , berberine sulfate, S-carboxymethylcysteine, curcumin, coloring, flavoring, a detergent (such as Polysorbate 20 (e.g., Tween® 20)), or any combination thereof. In some applications, the gargle fluid is carbonated. Alternatively or additionally, for some applications, a detergent, such as Polysorbate 20 (e.g., Tween® 20) is added to the gargled fluid after being gargled by the subject. Alternatively, liquid specimen sample  22  may comprise another type of biological fluid, such as blood (e.g., diluted blood), urine, stool (e.g., diluted stool), gastrointestinal (GI) fluid, or bronchoalveolar lavage fluid. 
     Alternatively, liquid specimen sample  22  comprises saliva not swabbed from the throat of a subject (i.e., the saliva was collected without swabbing the subject&#39;s throat). (The distinction between “swab” as a verb and as a noun is noted. A “swab” (as a noun) may be used to obtain saliva without “swabbing” (as a verb) the subject&#39;s throat. For example, the subject may suck on a swab, or a swab may be dipped in a container into which gargle fluid or saliva has been placed.) By contrast, in commonly-practiced techniques for testing for strep, the tonsils are swabbed. Further alternatively, liquid specimen sample  22  comprises liquid from a cultured medium containing a biological sample which had been incubated within tubular container  30  or incubated separately from the device and then added to tubular container  30 . 
     Liquid specimen sample  22  (e.g., saliva) may be spit directly by the subject into tubular container  30  or transferred by a healthcare worker from another container into which the subject spit. Alternatively, in the case of saliva, the saliva may be collected from the subject&#39;s mouth by having the subject suck on a swab or other absorbent collecting element, such as flocked swabs or cotton rolls. 
     For some applications in which the method does not comprise swabbing the throat of the subject, liquid specimen sample  22  is collected by drawing liquid specimen sample  22  out of an oral cavity of the subject via an anterior opening of the oral cavity by contacting one or more portions of the oral cavity with an absorbent material, e.g., a flocked or cotton swab, or a sponge (e.g., at a tip of a collector shaft), without swabbing the oropharynx of the subject. (For example, an ORAcollect®•RNA Saliva Collection Device (DNA Genotek Inc., a subsidiary of OraSure Technologies, Inc. (Bethlehem, Pa., USA)) may be used.) Optionally, the absorbent material is located on a tip of a collector shaft, and liquid specimen sample  22  is drawn out of the oral cavity via the anterior opening of the oral cavity using the absorbent material by inserting the tip of the collector shaft into the oral cavity. For some of these applications, liquid specimen sample  22  is drawn out of the oral cavity via the anterior opening of the oral cavity using the absorbent material by the subject sucking on the absorbent material. For example, the one or more portions of the oral cavity may include one or more of buccal mucosa, the tongue (e.g., under the tongue), the gums (e.g., the lower gums), and/or the palatal mucosa. For example, for swabbing the lower gums, absorbent material (e.g., at a tip of a collector shaft) may be rubbed back and forth along the lower gums several times. (The anterior opening of the oral cavity is the opening of the mouth between the lips, between outside the oral cavity and inside the oral cavity.) 
     Alternatively, liquid specimen sample  22  comprises an incubated culture medium containing a biological sample. 
     For some applications, filter  60  is advanced into collection vial  50  while filter  60  remains stationary with respect to a distal end of tubular container  30 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     For some applications, liquid specimen sample  22  is placed in tubular container  30  proximal to filter  60  that is disposed on proximal support surface  64  defined by filter support  62  that is disposed within tubular container  30 , such as shown in  FIGS.  1 A,  2 A,  6 A,  7 A, and  8 A . Plunger head  42  is distally advanced within tubular container  30  to drive the at least a portion of liquid specimen sample  22  through filter  60  and filtrate-passage openings  68  defined by filter support  62 , such as shown in  FIGS.  1 B-C ,  2 B-C,  6 B-C,  7 B, and  8 B. 
     For some applications, advancing filter  60  into collection vial  50  via plunger-head opening  44  and vial opening  52  comprises axially moving proximal portion  74  of shaft  72  and collection vial  50  with respect to each other, such that (a) proximal portion  74  of shaft  72  moves through (i) filter-support shaft-passage region  69  (e.g., filter-support opening  70 ) defined by filter support  62 , (ii) plunger-head opening  44 , and (iii) vial opening  52 , and (a) proximal end  75  of shaft  72  pushes filter  60  through plunger-head opening  44  into collection vial  50  via vial opening  52 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     For some applications, advancing filter  60  into collection vial  50  via plunger-head opening  44  and vial opening  52  comprises moving plunger head  42  and collection vial  50  within tubular container  30 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     For some applications, advancing filter  60  into collection vial  50  via plunger-head opening  44  and vial opening  52  comprises axially moving proximal portion  74  of shaft  72  of filtration assembly  24  and collection vial  50  with respect to each other, such that (a) proximal portion  74  of shaft  72  moves through plunger-head opening  44  and vial opening  52 , and (a) proximal end  75  of shaft  72  pushes filter  60  through plunger-head opening  44  into collection vial  50  via vial opening  52 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     Reference is made to  FIGS.  1 A-C  and  2 A-C. For some applications, collection vial  50  of sampling device  120  or  320  is positioned proximal to plunger head  42  such that vial opening  52  is in fluid communication with plunger-head opening  44 , such as shown in  FIGS.  1 A-C  and  2 A-C for sampling device  120 , and in  FIGS.  7 A-B  and  8 A-B for sampling device  320 , and plunger head  42  is distally advanced within tubular container  30 , while sampling device  20  is oriented such that proximal container opening  32  faces upward away from the Earth, to drive the at least a portion of liquid specimen sample  22  through filter  60 , such as shown in  FIGS.  1 B-C ,  2 B-C,  7 B, and  8 B. 
     Reference is made to  FIGS.  6 A-C . For some applications, collection vial  50  of sampling device  220  is positioned proximal to plunger head  42  such that fluid-tight frangible seal  276  of sampling device  20  removably blocks flow of liquid specimen sample  22  from plunger-head opening  44  into vial opening  52 , such as shown in  FIGS.  6 A-C . Advancing filter  60  into collection vial  50  via plunger-head opening  44  and vial opening  52  of collection vial  50  breaches frangible seal  276  such that vial opening  52  is in fluid communication with plunger-head opening  44 , such as shown in  FIG.  6 D . 
     Reference is again made to  FIGS.  1 A-G ,  2 A-G,  6 A-G,  7 A-F, and  8 A-F. For some applications, collection vial  50  is disengageably coupled to plunger  40 , and the method further comprises decoupling collection vial  50  from plunger  40  after advancing filter  60  into collection vial  50 , such as shown in  FIGS.  1 F,  2 F,  6 F,  7 E, and  8 E . 
     For some of these applications, collection vial  50  is decoupled from plunger  40  while plunger head  42  is within tubular container  30 , such as shown in  FIGS.  1 F,  2 F,  6 F,  7 E , and  8 E. This prevents exposure of plunger head  42  and any residual portion of liquid specimen sample  22  that was not driven through filter  60 . For some of these applications collection vial  50  is decoupled from plunger  40  ( a ) via proximal end  81  of plunger  40 , (b) while the plunger head is advanced as far as possible within the tubular container, and/or (c) without proximally withdrawing the plunger head within the tubular container. 
     For some applications, plunger head  42  is inserted into tubular container  30  while collection vial  50  is disposed partially within internal plunger space  86 , with axial portion  87  of collection vial  50  protruding proximally out of plunger-space proximal opening  90  of internal plunger space  86 . For some of these applications, plunger head  42  is distally advanced within tubular container  30  to drive the at least a portion of liquid specimen sample  22  through filter  60  by pushing on axial portion  87  of collection vial  50 . 
     For some of these applications in which plunger  40  comprises plunger rod  82  that is shaped so as to define internal plunger space  86 , such as described hereinabove, plunger head  42  is inserted into tubular container  30  while collection vial  50  is disposed at least partially within internal plunger space  86 , such as shown in  FIGS.  1 B,  2 B,  6 B,  7 B, and  8 B . For some applications, decoupling collection vial  50  from plunger  40  comprises removing collection vial  50  from internal plunger space  86  through plunger-space proximal opening  90  of internal plunger space  86 . 
     Reference is made to  FIG.  3   . For some of these applications, collection vial  50  is removably disposed partially within internal plunger space  86 , with an axial portion  87  of collection vial  50  protruding proximally out of plunger-space proximal opening  90  of internal plunger space  86 . Axial portion  87  of collection vial  50  includes end  89  of collection vial  50  opposite end  91  of collection vial  50  that defines vial opening  52 . Optionally, axial portion  87  of collection vial  50  protrudes proximally out of plunger-space proximal opening  90  by a distance D 3  of at least 4 cm. For some applications, such as shown in  FIGS.  1 A-E ,  2 A-E,  3 , and  6 A-E, axial portion  87  may be used as a handle for plunger  40 ; pushing on axial portion  87  distally advances plunger  40  within tubular container  30 . 
     For some of these applications in which plunger  40  comprises plunger rod  82 , such as described hereinabove, plunger head  42  is inserted into tubular container  30  while collection vial  50  is disposed alongside plunger rod  82  (configuration not shown). 
     For some applications, filter support  62  is slidable along tubular container  30 , and the method further comprises, after distally advancing plunger head  42  within tubular container  30  to drive the at least a portion of liquid specimen sample  22  through filter  60  and filtrate-passage openings  68  of filter support  62  (such as shown in  FIGS.  1 B-C ,  2 B-C,  6 B-C,  7 B, and  8 B), further distally advancing plunger head  42  within tubular container  30  such that plunger head  42  distally pushes filter support  62  within tubular container  30 , such as shown in  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D. 
     For some of these applications, such as shown in  FIGS.  1 A-G ,  2 A-G,  3 - 5 , and  6 A-G, plunger head  142  is disengageably coupled to distal end portion  184  of plunger rod  182 . For some of these applications, plunger head  142  becomes decoupled from plunger rod  182  as plunger head  142  distally pushes filter support  62  within tubular container  30 , such as shown in  FIGS.  1 D,  2 D, and  6 D . 
     For some applications in which axial portion  87  of collection vial  50  is used as a handle for plunger  140 , such as described above with reference to  FIGS.  1 A-E ,  2 A-E,  3 , and  6 A-E, pushing on axial portion  87  distally advances plunger head  142  while plunger rod  182  remains stationary with respect to tubular container  30  (for example, plunger rod  182  and/or tubular container  30  may be shaped so as to set a maximum distal advancement of plunger rod  182  within tubular container  30 , e.g., a proximal lip of plunger-space proximal opening  190  of internal plunger space  186  may have a greater diameter than that of tubular container  30 ). As a result, pushing on axial portion  87  distally advances plunger head  142  and decouples plunger head  142  from plunger rod  182 , as plunger head  142  distally pushes filter support  62  within tubular container  30 , such as shown in  FIGS.  2 D and  6 D . 
     For other applications, such as shown in  FIGS.  7 A-F ,  8 A-F, and  9 A-C, plunger head  342  is fixedly coupled to distal end portion  384  of plunger rod  382 , and does not become decoupled from plunger rod  382  as plunger head  342  distally pushes filter support  62  within tubular container  30 , such as shown in  FIGS.  7 C and  8 C . 
     For other applications in which sampling device  320  comprises proximal grip  392 , such as described hereinabove with reference to  FIGS.  9 A-C , pushing on proximal grip  392  distally advances plunger  340 , causing plunger head  342  to distally push filter support  62  within tubular container  30 , such as shown in  FIGS.  7 C and  8 C . 
     For some applications, the method further comprises sealing vial opening  52  with collection vial cap  80  after filter  60  has been advanced into collection vial  50 , such as shown in  FIGS.  1 G,  2 G,  6 G,  7 F, and  8 F . 
     For some applications, the method further comprises bathing filter  60  with liquid  1010  within collection vial  50  after filter  60  has been advanced into collection vial  50 , such as shown in  FIGS.  1 G,  2 G,  6 G,  7 F, and  8 F . For example, liquid  1010  may be selected from the group consisting of: a lysis buffer, saline solution, and transport medium. 
     For some applications, the method further comprises, after filter  60  has been advanced into collection vial  50 , detecting the presence of a biological particulate trapped by filter  60 . For example, the biological particulate may be selected from the group consisting of: a virus, a bacterium, a microorganism, a fungus, a spore, a mite, a biological cell, a biological antigen, a protein, a protein antigen, and a carbohydrate antigen. 
     For some applications, detecting the presence of the biological particulate trapped by filter  60  comprising using a lateral flow immunoassay test strip to detect the presence of the biological particulate trapped by filter  60 . 
     In some applications of the present invention, internal plunger space  86  of plunger rod  82  is shaped so as to define an internal collection chamber, into which filter  60  is advanced (configuration not shown). In these applications, sampling device  20  typically does not comprise collection vial  50  (configuration not shown). 
     In some applications of the present invention, collection vial  50  is removable from plunger  40  through plunger-head opening  44  (configuration not shown). For some of these applications, collection vial  50  is removable from internal plunger space  86  through plunger-head opening  44  (configuration not shown). 
     In some applications of the present invention, collection vial  50  is fixedly coupled to plunger  40  (configuration not shown). 
     In some applications of the present invention, proximal portion  74  of shaft  72  is axially slidable with respect to tubular container  30  (configuration not shown). 
     Reference is now made to  FIGS.  10 A and  10 B , which are schematic illustrations of another configuration of sampling device  20 , in accordance with an application of the present invention. In this configuration, filter  60  is a first filter  60 A, and filtration assembly  24  further comprises a second filter  60 B, disposed proximally to first filter  60 A, such as in contact with a proximal surface of first filter  60 A, as shown. Optionally, filtration assembly  24  still further comprises one or more additional filters (configuration not shown). 
     For some applications in which sampling device  20  is configured such that movement of plunger head  42  and collection vial  50  within tubular container  30  advances filter  60  into collection vial  50 , such as described hereinabove, relative axial movement between shaft  72  and collection vial  50  causes proximal portion  74  of shaft  72  to push first filter  60 A and second filter  60 B into collection vial  50  via vial opening  52 , such as shown in  FIG.  10 B . 
     For some applications, first and second filters  60 A and  60 B have different nominal pore sizes, as defined hereinabove. For these applications, second filter  60 B typically has a larger nominal pore size than first filter  60 A. For example, when the filters are used for capturing free virus, virions, or viral particles by size-based filtration, first filter  60 A may have a pore size of between 0.01 and 0.3 microns and/or a molecular weight cut off of between 10 kDa and 500 kDa, and/or second filter  60 B may have a nominal pore size of between 30 microns and 1.5 mm, or the other pore sizes provide for the large-pore filters described in above-mentioned U.S. Provisional Application 63/117,294, filed Nov. 23, 2020. 
     For other applications, first filter  60 A may have a pore size of between 0.2 and 2.0 microns, for example, when the filters are used for capturing bacteria by size-based filtration. 
     For some applications, first filter  60 A may comprise a fragile material, such as glass fibers, and second filter  60 B may comprise a sturdier material, such as a polymer. Second filter  60 B may mechanically support first filter  60 A and prevent first filter  60 A from breaking apart as proximal portion  74  of shaft  72  pushes the filters into collection vial  50 . 
     For some of these applications, first and second filters  60 A and  60 B are coupled together at one or more locations on the filters, such that second filter  60 B helps draw first filter  60 A into collection vial  50 . For example, the filters may be coupled together by gluing (using one or more drops of glue, such as a cyanoacrylate), soldering, overmolding, and/or mechanically connecting interlocking parts. Optionally, one or more filter supports are coupled together with first and second filters  60 A and  60 B, either between, above, and/or below the filters. Optionally, improving sealing between the perimeter of one or more of the filters with inner wall  34  of tubular container  30  may be achieved by reducing and/or filling spacing between the filter fibers, such as heating and compression, overmolding, and/or filling with adhesive material. For example, for configurations in which at least one of the filters comprises a meltable material, such as a polymer, the filter may be melted around its perimeter (edge) to achieve a better seal with inner wall  34  of tubular container  30 . 
     For some applications in which second filter  60 B comprises a sturdier material, such as a polymer, second filter  60 B may be cut, such as in one or more lines. Such cutting may help prevent plugging of collection vial  50  by second filter  60 B after insertion thereinto, such as shown in  FIGS.  1 G,  2 G,  6 G,  7 F, and  8 F . 
     Reference is now made to  FIG.  11   , which is a schematic illustration of a plunger  440  fully inserted into a tubular container  430 , in accordance with an application of the present invention.  FIG.  11    shows plunger  440  maximally distally advanced with respect to tubular container  430 . Plunger  440  comprises a plunger rod  482 , which has a distal end portion to which a plunger head is coupled. Optionally, the features of plunger  440  and tubular container  430  may be combined with any of the plungers and tubular containers described herein. 
     Plunger  440  is shaped so as to define first ratchet teeth  493  that face radially inwardly and are configured to engage corresponding second ratchet teeth  495  that are defined by an external surface of tubular container  430  and face radially outward. Plunger  440  and tubular container  430  may respectively comprise one or more sets of first and second ratchet teeth  493  and  495  (for example, two sets, as shown). For some applications, plunger  440  comprises one or more teeth supports  497 , which extend proximally alongside at least a portion of plunger rod  482 , separated from plunger rod  482  to provide a space for insertion of tubular container  430 . The one or more teeth supports  497  are shaped so as to define the one or more sets of first ratchet teeth  493 . 
     Typically, first and second ratchet teeth  493  and  495  are configured to allow only distal advancement of plunger  440  with respect to tubular container  430  and to prevent proximal withdrawal of the plunger  440  with respect to tubular container  430 . This one-way limitation may prevent the user from removing plunger  440  from tubular container  430  after distal advancement of plunger  440  within tubular container  430 . 
     Reference is now made to  FIG.  12   , which is a schematic illustration of a plunger  540  fully inserted into a tubular container  530 , in accordance with an application of the present invention.  FIG.  12    shows plunger  540  maximally distally advanced with respect to tubular container  530 . Plunger  540  comprises a plunger rod  582 , which has a distal end portion to which a plunger head is coupled. Optionally, the features of plunger  540  and tubular container  530  may be combined with any of the plungers and tubular containers described herein. 
     Plunger  540  is shaped so as to define a first thread (configuration not shown) or one or more first thread segments  593  (as shown) that face radially inwardly and are configured to engage a corresponding second thread  595  that is defined by an external surface of tubular container  530  and faces radially outward. For some applications, plunger  540  comprises one or more thread supports  597 , which extend proximally alongside at least a portion of plunger rod  582 , separated from plunger rod  582  to provide a space for insertion of tubular container  530 . The one or more thread supports  597  are shaped so as to define the first thread (configuration not shown) or the one or more first thread segments  593 , respectively (as shown). Providing the threads may help the user apply sufficient and/or correct pressure to liquid specimen sample  22  for pushing liquid specimen sample  22  through a filter within tubular container  530 . 
     Reference is now made to  FIGS.  13 A-D , which are schematic illustrations of filters  660 A,  660 B,  660 C, and  660 D, respectively, in accordance with respective applications of the present invention. Filters  660 A,  660 B,  660 C, and  660 D are respective implementations of filter  60 , described herein, and may be substituted for filter  60  in any of the filtration assemblies described herein. 
     Filters  660 A,  660 B,  660 C, and  660 D are shaped so as to define respective pluralities of slits  662 A,  662 B,  662 C, and  662 D therethrough. These slits may improve passage of liquid  1010  through the filter during bathing of the filter in collection vial  50  after the filter has been placed in collection vial  50 , such as described hereinabove  FIGS.  1 G,  2 G,  6 G,  7 F , and  8 F. As can be seen in  FIGS.  2 D-G ,  6 D-G,  8 C-F,  10 B,  19 D-G,  20 , and  21 , during insertion of the filter into collection vial  50 , the filter may be transformed into a cuplike shape from its initial flat shape while disposed on the filter support within the filtration assembly. This transformation may cause the filter to separate along the slits, creating openings through which liquid  1010  can pass. 
     Typically, when liquid specimen sample  22  is driven through the filters, liquid specimen sample  22  substantially does not pass through slits  662 A,  662 B,  662 C, and  662 D, but instead passes through pores of the filters, because the flat shape of the filters holds the edges of the slits together. This non-passage of liquid specimen sample  22  through slits in filters in a pattern similar to that of slits  662 C was observed in experiments conducted by the inventors using gargled fluid as the liquid specimen sample. 
     For some applications, slits  662 A,  662 B,  662 C, and  662 D include respective radial-inward ends  664  and radially-outward ends  666 , radially-inward ends  664  closer to a center  668  of the filters than are radially-outward ends  666 . Optionally, radially-outward ends  666  are located on a perimeter  670  of the filters. 
     For some applications, the slits are curved, such as slits  662 B and  662 D. For some applications, the slits are straight, such as slits  662 C. For some applications, the slits include segments angled with respect to one another, such as slits  662 A. 
     For some applications, filters  660 A,  660 B,  660 C, and  660 D are shaped so as to define central regions  672  that are not shaped so as to define slits  662 A,  662 B,  662 C, and  662 D, respectively. Central regions  672  may have an area of at least 20 mm2, no more than 75 mm2, and/or between 20 and 75 mm2, and/or between 75% and 150% of an area of filter-support shaft-passage region  69  (e.g., filter-support opening  70 ). 
     Reference is now made to  FIGS.  14 A-B , which are a schematic illustration and a schematic cross-sectional illustration of an alternative configuration of coupling between filter support  62  and shaft  72 , in accordance with an application of the present invention. In this configuration, filter support  62  and shaft  72  are releasably axially locked with respect to each other such that:
         the first distal advancement of plunger head  42  within tubular container  30 , described hereinabove with reference to the transitions between  FIGS.  1 B and  1 C , between  FIGS.  2 B and  2 C , between  FIGS.  6 B and  6 C , between  FIGS.  7 A and  7 B , and between  FIGS.  8 A and  8 B , does not axially unlock filter support  62  and shaft  72  with respect to each other, and   the further second distal advancement of plunger head  42 , described hereinabove with reference to  FIGS.  1 D-E ,  2 D-E,  6 D-E,  7 C-D, and  8 C-D, axially unlocks filter support  62  and shaft  72  with respect to each other, thereby enabling axial movement with respect to each other.       

     For some applications, filtration assembly  24  comprises one or more release controls  700 , which are configured to axially unlock filter support  62  and shaft  72  with respect to each other upon actuation of the one or more release controls  700  by the further second distal advancement of plunger head  42 . For example, the one or more release controls  700  may comprise one or more pins  702 , respectively, which extend proximally, and are actuated by being pushed distally. 
     For some applications, a locking assembly  710  is provided that comprises the one or more release controls  700  and one or more prongs  712  that engage shaft  72  (for example, respective indentations in shaft  72 ) when locking assembly  710  is in a locked state, such as shown in  FIGS.  14 A-B . Actuation of the one or more release controls  700  disengages the one or more prongs  712  from shaft  72 , thereby transitioning locking assembly  710  to an unlocked state in which filter support  62  and shaft  72  can axially move with respect to each other (state not shown). 
     Reference is now made to  FIG.  15   , which is a schematic illustration of a testing kit  1000 , in accordance with an application of the present invention. Testing kit  1000  comprises sampling device  20  (e.g., sampling device  120 , as shown), sampling device  220 , sampling device  320 , sampling device  1320 , sampling device  1420 , sampling device  1520 , sampling device  1620 , or sampling device  1720  (not shown) and a liquid  1010  for bathing filter  60  within a collection vial (or an extraction tube, such as in the case of sampling device  1720 ). Liquid  1010  may, for example, be selected from the group consisting of: a lysis buffer, saline solution (e.g., phosphate buffered saline (PBS)), and transport medium (e.g., universal transport medium or a viral transport medium). 
     Testing kit  1000  may be used, for example, for collecting liquid specimen sample  22  from the subject and sending at least a portion of the specimen sample to a remote laboratory in the liquid in collection vial  50 , such as for performing Polymerase Chain Reaction (PCR) testing for particulate in liquid specimen sample  22 . 
     The particulate may, for example, be a virus (e.g., an Influenza virus, or a coronavirus, such as SARS-CoV-2), a bacterium (e.g.,  Streptococcus  bacteria, such as  Streptococcus pyogenes  (Strep A)), a microorganism, an antigen, a human cell, a cellular biomarker, a hormone, a chemical mediator from cells (e.g., a mediator of inflammation), a pollen, mucous, saliva, sputum, a respiratory particle, droplets derived from the upper and lower airways, a nucleic acid including DNA and RNA, and a chemical originating from external vapors. When the particulate is a microorganism, the microorganism may be either a pathogenic microorganism or a non-pathogenic microorganism or both, for example, viruses, bacteria, protozoa, and fungi. When the particulate is a human cell, the human cell may be an epithelial cell, for example, a columnar epithelial cell primarily derived from the nasal cavity and a squamous epithelial cell primarily derived from the oral cavity. The human cell may also be a cellular responder of the immune system, for example, neutrophils, eosinophils, lymphocytes, monocytes, macrophages, mast cells, and histocytes. 
     Optionally, a separate liquid container  1012  is provided that contains liquid  1010 , such as shown. Alternatively, liquid  1010  is contained in collection vial cap  80  and released upon placement of cap  80  on collection vial  50  (configuration not shown). 
     Reference is now made to  FIGS.  16 A-C , which are schematic illustrations of a testing kit  1100 , in accordance with an application of the present invention. Testing kit  1100  comprises a sampling device  1120  and liquid  1010  for bathing filter  60 , such as described hereinabove with reference to  FIG.  15   . Other than as described below, sampling device  1120  may be identical to sampling device  20 , described hereinabove, or to sampling device  1320 , described hereinbelow, and may implement any of the features of either of these sampling devices, mutatis mutandis. Sampling device  1120  comprises a collection vial  1150 . Other than as described below, collection vial  1150  is identical to collection vial  50 , described hereinabove, and may implement any of the features thereof, mutatis mutandis. 
     Collection vial  1150  comprises an internal chamber  1151 , which contains liquid  1010  and is configured to prevent spillage of liquid  1010  out of collection vial  1150  regardless of an orientation of collection vial  1150 . 
     Typically, internal chamber  1151  contains a volume of liquid  1010  of at least 0.1 ml (e.g., at least 2 ml, such as 3 ml), no more than 5 ml, and/or between 0.1 ml (e.g., 2 ml) and 5 ml, such as 3 ml. 
     For some applications, sampling device  1120  further comprises a collection vial cap  1180 , which is configured to seal vial opening  52 , such as shown in the transition between  FIGS.  16 B and  16 C . For some of these applications, collection vial  1150  and collection vial cap  1180  are configured such that placement of collection vial cap  1180  on vial opening  52  of collection vial  1150  automatically releases liquid  1010  from internal chamber  1151 , such as by rupturing, puncturing, or otherwise breaking at least one wall of internal chamber  1151 , or opening a valve of internal chamber  1151 , such as by a rotational force generated by rotation of collection vial cap  1180  (configuration not shown). For some applications, a method is provided that comprises, after filter  60  has been advanced into collection vial  1150 , sealing vial opening  52  with collection vial cap  1180  so as to automatically release liquid  1010  from internal chamber  1151 . 
     For example, collection vial cap  1180  may comprise a shaft  1153  that extends from an inner surface  1155  of collection vial cap  1180 , and is configured to puncture internal chamber  1151  when collection vial cap  1180  is placed on vial opening  52 . Shaft  1153  may or may not comprise a sharp tip  1157 . 
     Reference is now made to  FIG.  17   , which is a schematic illustration of a testing kit  1200 , in accordance with an application of the present invention. Testing kit  1200  comprises sampling device  20  (as shown) or sampling device  1320 , sampling device  1420 , sampling device  1520 , sampling device  1620 , or sampling device  1720  (not shown) and a test  1220  (e.g., a diagnostic test), which is configured to test for the present of a particulate in material trapped by filter  60 . The particulate may, for example, be any of the particulates mentioned hereinabove. For some applications, test  1220  comprises a lateral flow immunoassay test strip, which is configured to detect the presence of the particulate (such as by detecting protein antigen, e.g., from a virus), and, optionally, one or more reagents for use with the lateral flow immunoassay strip. 
     Reference is made to  FIGS.  15 ,  16 A -B, and  17 . For some applications, such as shown in  FIG.  17   , testing kit  1000 ,  1100 , or  1200  further comprises a container  1265  containing oral wash fluid  1267 . The subject may optionally gargle oral wash fluid  1267 , and use sampling device  20  or sampling device  1320  to filter the gargled oral wash fluid. Typically, oral wash fluid  1267  comprises a non-irritant solution; for example, the non-irritant solution may comprise or consist of water. In some applications, the non-irritant solution comprises saline solution that may be hypertonic, isotonic, or hypotonic, for example, a phosphate-buffered saline solution. 
     For some applications, any of the collection vials described herein may comprise one or more small rigid spheres, contained within the vial. After liquid  1010  is placed or released within the collection vial and filter  60  is placed in the collection vial, such as described herein, the collection vial is agitated, such as shaken, which causes the spheres to break apart the filter, such as by macerating, crushing, shredding, or mashing the filter. This technique may be particularly useful when the filter comprises a fragile material, such as glass fibers. Optionally, the one or more spheres comprise a metal. 
     Reference is now made to  FIGS.  18 A-G , which are schematic illustrations of a sampling device  1320  for concentrating liquid specimen sample  22 , and a method of using sampling device  1320 , in accordance with respective applications of the present invention. 
     Reference is also made to  FIGS.  19 A-G , which are schematic cross-sectional illustrations of sampling device  1320  and the method of using sampling device  1320 , in accordance with respective applications of the present invention. 
     Reference is further made to  FIG.  20   , which is an enlarged schematic illustration of sampling device  1320  in the state shown in  FIGS.  18 E and  19 E , in accordance with an application of the present invention. 
     Sampling device  1320  typically comprises a filtration assembly  1324  and collection vial  50 , which may have any of the properties described hereinabove. Filtration assembly  1324  comprises a tubular container  1330 , a plunger  1340 , and filter  60 , which is disposed in tubular container  1330  and may have any of the properties described hereinabove with reference to  FIGS.  1 A- 9 B . Tubular container  1330  is shaped so as to define a proximal container opening  1332  for receiving liquid specimen sample  22 . Optionally, proximal container opening  1332  has a conical or funnel shape to facilitate receipt of liquid specimen sample  22 , which may, for example, be expressed (e.g., spit) from subject&#39;s mouth into tubular container  1330 , or transferred to tubular container  1330  from a collection container. Optionally, the funnel shape of proximal container opening  1332  is similar to funnel-shaped proximal opening  36  shown in FIG. 1 of US Patent Application Publication 2019/0381498 to Fruchter et al., which is incorporated herein by reference. Tubular container may be cylindrical, as shown, or may alternatively have another, non-circular cross-sectional shape. Tubular container  1330  is also shaped so as to define an inner wall  1334 . 
     For some applications, filtration assembly  1324  comprises a plurality of filters (configuration not shown). Optionally, two or more of the plurality of filters touch one another, or are separated by one another by one or more thin spacers (e.g., having a thickness of at least 0.05 mm, no more than 1 mm, and/or between 0.05 and 1 mm. Alternatively or additionally, two or more of the plurality of filters are spaced apart from another, which case filtration assembly  1324  optionally comprises a corresponding number of filter supports. 
     Typically, tubular container  1330  has an internal volume of at least 0.5 ml (e.g., at least 1 ml, such as at least 5 ml), no more than 500 ml (e.g., no more than 70 ml), and/or between 0.5 ml (e.g., 1 ml or 5 ml) and 500 ml (e.g., 70 ml). 
     For some applications, tubular container  1330  does not comprise a Luer lock or any other type of needle-coupling mechanism. 
     Plunger  1340  comprises a plunger head  1342 . Plunger  1340  is insertable into tubular container  1330  via proximal container opening  1332 , such that a lateral surface  1346  of plunger head  1342  (labeled in  FIG.  20   ) forms a fluid-tight movable seal with inner wall  1334 . To this end, lateral surface  1346  may comprise an elastomeric material, such as natural rubber, synthetic rubber, a thermoplastic elastomer, or a combination thereof. 
     Collection vial  50  is disengageably coupled to filtration assembly  1324 , such as to tubular container  1330  of filtration assembly  1324 , or to a filter support  1362  of filtration assembly  1324 , described hereinbelow. Once collection vial  50  has been decoupled from filtration assembly  1324 , a diagnostic test may be performed for the presence of particulate trapped by filter  60 , which is now in collection vial  50 . For some applications, such as for transporting collection vial  50  to a remote diagnostic laboratory, sampling device  1320  further comprises collection vial cap  80 , which is configured to seal vial opening  52 , such as shown in  FIGS.  18 G and  19 G . 
     Filtration assembly  1324  is configured such that movement (typically distal advancement) of plunger head  1342  within tubular container  1330 , when liquid specimen sample  22  is contained in tubular container  1330  and filter  60  is disposed in tubular container  1330 , pushes at least a portion of liquid specimen sample  22  through filter  60 . Filter  60  is configured to concentrate at least a portion of liquid specimen sample  22  onto filter  60 , while allowing filtrate  61  to pass through filter  60 . Typically, distal advancement of plunger  1340  within tubular container  1330  applies pressure to drive (e.g., push) at least a portion of liquid specimen sample  22  contained in tubular container  1330  through filter  60 , such as shown in the transitions between  FIGS.  18 B and  18 C  and between  FIGS.  19 B and  19 C . 
     Sampling device  1320  is configured such that filter  60  is advanceable into (e.g., entirely into) collection vial  50  via vial opening  52  while collection vial  50  is disengageably coupled to filtration assembly  1324 , such as shown in  FIGS.  18 D-E  and  19 D-E. 
     For some applications, sampling device  1320  is configured such that filter  60  is advanceable into collection vial  50  via vial opening  52  while plunger head  1342  is within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. For some of these applications, sampling device  1320  is configured such that filter  60  is advanceable into collection vial  50  via vial opening  52  while plunger head  1342  is advanced as far as possible within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. Alternatively or additionally, for some applications, sampling device  1320  is configured such that filter  60  is advanceable into collection vial  50  via vial opening  52  without any proximal withdrawal of plunger head  1342  within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. 
     For some applications, filtration assembly  1324  is configured such that when plunger head  1342  is within tubular container  1330 , fluid communication is blocked between (a) tubular container  1330  distal to plunger head  1342  and (b) proximal container opening  1332 . For some of these applications, filter  60  is advanceable into collection vial  50  while plunger head  1342  is within tubular container  1330 . 
     Typically, filtration assembly  1324  further comprises a waste liquid receptacle  1356  for receiving filtrate  61 . For some applications, a distal portion of tubular container  1330  is shaped so as to define waste liquid receptacle  1356 , such as shown in the drawings. For other applications, waste liquid receptacle  1356  is provided as a separate container coupled in fluid communication with tubular container  1330  downstream (distally) to filter  60 . 
     Optionally, waste liquid receptacle  1356  is shaped so as to define an opening  1358  through an external wall of waste liquid receptacle  1356  to release displaced air. For example, opening  1358  may be located on a side portion of the external wall, typically above the highest level that filtrate  61  is expected to reach during ordinary use of the device. For some applications, waste liquid receptacle  1356  comprises an air filter (e.g., an N98 filter) that is disposed to filter air that passes out of waste liquid receptacle  1356  through opening  1358  (not shown). Alternatively or additionally, for some applications, waste liquid receptacle  1356  comprises a one-way pressure-sensitive valve disposed in opening  1358 . 
     As mentioned above, collection vial  50  typically is not shaped so as to define any pressure-release openings and does not comprise any pressure-release valves. 
     For some applications, waste liquid receptacle  1356  contains a disinfectant or a liquid-absorbing material. 
     For some applications, sampling device  1320  further comprises a shaft  1372 , and sampling device  1320  is configured such that that a distal portion  1377  of shaft  1372  is axially movable through vial opening  52  so as to advance filter  60  into collection vial  50  via vial opening  52 , such as shown in  FIGS.  18 D-E  and  19 D-E. 
     For some of these applications, shaft  1372  is coupled to plunger  1340 . Typically, sampling device  1320  is configured such that shaft  1372  remains axially stationary with respect to plunger head  1342  during the movement of plunger head  1342  within tubular container  1330 , such as shown in the transitions between  FIGS.  18 B and  18 C  and between  FIGS.  19 B and  19 C . 
     For some of these applications, plunger head  1342  is shaped so as to define a plunger-head opening  1344  through plunger head  1342 , and shaft  1372  is slidable through plunger-head opening  1344 , such as shown in the transitions between  FIGS.  18 C and  18 E  and between  FIGS.  19 C and  19 E . Typically, plunger-head opening  1344  forms a fluid-tight movable seal with an outer surface of shaft  1372 . 
     For some applications, sampling device  1320  further comprises a fluid-tight frangible seal  1376 . Collection vial  50  is positioned distal to filter  60  such that frangible seal  1376  removably blocks liquid flow into vial opening  52 . 
     Frangible seal  1376  may be coupled to filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ), described hereinbelow (such as shown), vial opening  52  (configuration not shown), another element disposed between filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) and vial opening  52  (configuration not shown), or a combination of these locations. 
     For example, frangible seal  1376  may comprise a pliable material (such as silicone) that is easily torn or a rigid material that is easily broken (e.g., shaped so as define slits to aid in breaking). 
     For some applications, filtration assembly  1324  further comprises a filter support  1362 , which is disposed within tubular container  1330 . Filter support  1362  is shaped so as to define:
         a proximal support surface  1364 , which may be perpendicular to a central longitudinal axis of tubular container  1330  (as shown), or may be angled with respect to the central longitudinal axis (configuration not shown), and   a plurality of filtrate-passage openings  1368  through filter support  1362 .       

     Filter  60  is disposed on proximal support surface  1364 . 
     For some of these applications, filter support  1362  is shaped so as to further define a filter-support shaft-passage region  1369 , which, for some applications, is shaped so as to define a filter-support opening  1370  through filter support  1362 . For some of these applications, collection vial  50  is positioned distal to filter  60  such that frangible seal  1376  removably blocks liquid flow through filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) into vial opening  52 , such that upon breaching of frangible seal  1376  vial opening  52  is in fluid communication with filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ). 
     Filter-support shaft-passage region  1369  and filter-support opening  1370  may implement any of the features of filter-support shaft-passage region  69  and filter-support opening  70 , respectively, as described hereinabove. In configurations in which frangible seal  1376  is provided, filter-support shaft-passage region  1369  is typically shaped so as to define filter-support opening  1370 . 
     Typically, a cross-sectional area of filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) is substantially larger than an average cross-sectional area of filtrate-passage openings  1368 ; for example, the cross-sectional area of filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) may be at least 10 times, such as at least 25 times, the average cross-sectional area of filtrate-passage openings  1368 . 
     For some applications:
         the cross-sectional area of filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) is between 20 and 75 mm2,   the average cross-sectional area of filtrate-passage openings  1368  is between 0.5 and 1.5 mm2, and/or   For some applications, a cross-sectional area of filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) is between 2.5% and 20% of a cross-sectional area of proximal support surface  1364  of filter support  1362 .       

     For some applications in which filtration assembly  1324  comprises waste liquid receptacle  1356 , waste liquid receptacle  1356  is disposed downstream of filter support  1362 , and filter support  1362  is shaped so as to define filtrate-passage openings  1368  through filter support  1362  into waste liquid receptacle  1356 . Typically filter support  1362  is not shaped so as to define filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) through filter support  1362  into waste liquid receptacle  1356 . 
     For some applications in which sampling device  1320  further comprises shaft  1372 , filter support  1362  and shaft  1372  are configured such that that distal portion  1377  of shaft  1372  is axially movable through filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) and vial opening  52  so as to breach of frangible seal  1376  and advance filter  60  into collection vial  50  via vial opening  52 , such as shown in  FIGS.  18 D and  19 D . 
     For some of these applications, distal portion  1377  of shaft  1372 , filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ), and vial opening  52  are coaxial. Alternatively or additionally, for some of these applications, distal portion  1377  of shaft  1372 , filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ), and vial opening  52  are coaxial with or parallel to the central longitudinal axis of tubular container  1330 . 
     For some applications, a cross-sectional area of distal portion  1377  of shaft  1372  is between 80% and 110% of a cross-sectional area of filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ). 
     For some applications, such as shown in  FIGS.  18 A-G ,  19 A-G, and  20 , and labeled in  FIGS.  18 A,  19 A, and  20   , plunger  1340  comprises a plunger rod  1382 , which has a distal end portion  1384  to which plunger head  1342  is coupled. Plunger rod  1382  and plunger head  1342  may be fabricated as a single integral piece, or as two pieces fixed together during manufacture. Plunger  1340  has a proximal end  1381 . 
     For some of these applications, plunger rod  1382  is shaped so as to define an internal plunger space  1386 , and shaft  1372  is removably disposed at least partially within internal plunger space  1386 . For some of these applications, a proximal end  1388  of plunger rod  1382  is shaped so as to define a plunger-space proximal opening  1390  of internal plunger space  1386 , and shaft  1372  is slidably disposed at least partially within internal plunger space  1386 . Typically, a proximal portion  1374  of shaft  1372  is accessible via plunger-space proximal opening  1390  of internal plunger space  1386 . 
     For some applications, sampling device  1320  is configured such that collection vial  50  is decouplable from filtration assembly  1324  while plunger head  1342  is within tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . For some of these applications, sampling device  1320  is configured such that collection vial  50  is decouplable from filtration assembly  1324  while plunger head  1342  is advanced as far as possible within tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . Alternatively or additionally, for some applications, sampling device  1320  is configured such that collection vial  50  is decouplable from filtration assembly  1324  without any proximal withdrawal of plunger head  1342  within tubular container  1330 , also such as shown in  FIGS.  18 F and  19 F . 
     For some applications, sampling device  1320  is configured such that collection vial  50  is decouplable from filtration assembly  1324  by distal movement of collection vial  50  with respect to tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . 
     For some applications in which filtration assembly  1324  further comprises waste liquid receptacle  1356 , collection vial  50  is disposed at least partially alongside waste liquid receptacle  1356 , such as shown in  FIGS.  18 A and  19 A  (when sampling device  1320  is in its initial state, which is typically set during manufacture thereof). Typically, collection vial  50  extends distally beyond a distal end  1357  of waste liquid receptacle  1356 . 
     For some applications, waste liquid receptacle  1356  surrounds collection vial  50 , such as shown in  FIGS.  18 A and  19 A . For some of these applications, collection vial  50  extends distally beyond and protrudes from distal end  1357  of waste liquid receptacle  1356 . Even though waste liquid receptacle  1356  surrounds collection vial  50 , the outer surface of collection vial  50  is not in fluid communication with the internal chamber of waste liquid receptacle  1356 , such that the outer surface of collection vial  50  does not get wet and is not exposed to potentially infection biological substances. 
     For some applications, sterile packaging is provided, in which at least sampling device  1320  is removably disposed. 
     Reference is made to  FIG.  21   , which is a schematic illustration of another configuration of sampling device  1320  in the state shown in  FIGS.  18 E and  19 E , in accordance with an application of the present invention. In this configuration, sampling device  1320  comprises frangible seal  1376 , and further comprises liquid  1010  contained in collection vial  50 , for bathing filter  60  within collection vial  50 . For example, liquid  1010  may be selected from the group consisting of: a lysis buffer, saline solution, and transport medium. 
     Reference is again made to  FIGS.  18 A-G  and  19 A-G. In some applications of the present invention, a method for concentrating liquid specimen sample  22  is provided, the method comprising:
         placing liquid specimen sample  22  in tubular container  1330  of filtration assembly  1324 , proximal to filter  1360  that is disposed within tubular container  1330 , such as shown in  FIGS.  18 A and  19 A ;   inserting plunger head  1342  of plunger  1340  into tubular container  1330  via proximal container opening  1332  of tubular container  1330 , while collection vial  50  is disengageably coupled to the filtration assembly  1324 , such that lateral surface  1346  of plunger head  1342  forms a fluid-tight movable seal with inner wall  1334  of tubular container  1330 , such as shown in  FIGS.  17 B and  19 B ; plunger head  42  is shaped so as to define plunger-head opening  44  through plunger head  42 ;   distally advancing plunger head  1342  within tubular container  1330  to drive at least a portion of liquid specimen sample  22  through filter  60 , such as shown in  FIGS.  18 C and  19 C ;   advancing filter  60  into (such as entirely into) collection vial  50  via vial opening  52  of collection vial  50  while collection vial  50  is disengageably coupled to filtration assembly  1324 , such as shown in  FIGS.  18 D-E  and  19 D-E; and   thereafter, decoupling collection vial  50  from filtration assembly  1324 , such as shown in  FIGS.  18 F and  19 F .       

     For some applications, liquid specimen sample  22  is received from a subject&#39;s mouth. For some applications, liquid specimen sample  22  comprises gargled fluid, such as described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G, and  6 A-G. Alternatively, liquid specimen sample  22  comprises saliva not swabbed from the throat of a subject, or obtained such as described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G, and  6 A-G. Liquid specimen sample  22  (e.g., saliva) may be spit directly by the subject into tubular container  1330  or transferred by a healthcare worker from another container into which the subject spit. Alternatively, in the case of saliva, the saliva may be collected from the subject&#39;s mouth by having the subject suck on a swab or other absorbent collecting element, such as flocked swabs or cotton rolls. 
     For some applications in which the method does not comprise swabbing the throat of the subject, liquid specimen sample  22  is collected by drawing liquid specimen sample  22  out of an oral cavity of the subject via an anterior opening of the oral cavity, such as described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G, and  6 A-G. 
     For some applications, filter  60  is advanced into collection vial  50  via vial opening  52  while plunger head  1342  is within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. For some of these applications, filter  60  is advanced into collection vial  50  via vial opening  52  while plunger head  1342  is advanced as far as possible within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. Alternatively or additionally, for some of these applications, filter  60  is advanced into collection vial  50  via vial opening  52  without proximally withdrawing plunger head  1342  within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. 
     For some applications in which filtration assembly  1324  is configured such that when plunger head  1342  is within tubular container  1330 , fluid communication is blocked between (a) tubular container  1330  distal to plunger head  1342  and (b) proximal container opening  1332 , filter  60  is advanced into collection vial  50  via vial opening  52  while plunger head  1342  is within tubular container  1330 , such as shown in  FIGS.  18 D-E  and  19 D-E. 
     For some applications in which sampling device  1320  further includes shaft  1372 , filter  60  is advanced into collection vial  50  by axially moving distal portion  1377  of shaft  1372  through vial opening  52 , such as shown in  FIGS.  18 D-E  and  19 D-E. 
     For some applications in which shaft  1372  is coupled to plunger  1340 , plunger head  1342  is distally advanced within tubular container  1330  while shaft  1372  remains axially stationary with respect to plunger head  1342 , such as shown in  FIGS.  18 A-C  and  19 A-C. 
     For some applications, filter  60  is advanced into collection vial  50  by axially moving distal portion  1377  of shaft  1372  through filter-support shaft-passage region  1369  (e.g., filter-support opening  1370 ) and vial opening  52  so as to breach of frangible seal  1376  and advance filter  60  into collection vial  50  via vial opening  52 . 
     Such as described above, for some applications, plunger  1340  comprises plunger rod  1382 , which is shaped so as to define internal plunger space  1386 , shaft  1372  is slidably disposed at least partially within internal plunger space  1386 , and proximal end  1388  of plunger rod  1382  is shaped so as to define plunger-space proximal opening  1390  of internal plunger space  1386 . For some applications, the method further comprises accessing proximal portion  1374  of shaft  1372  via plunger-space proximal opening  1390  of internal plunger space  1386 , such as in order to axially advance shaft  1372 . 
     For some applications, decoupling collection vial  50  is decoupled from filtration assembly  1324  while plunger head  1342  is within tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . For some of these applications, collection vial  50  is decoupled from filtration assembly  1324  while plunger head  1342  is advanced as far as possible within tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . Alternatively or additionally, for some of these applications, collection vial  50  is decoupled from filtration assembly  1324  without proximally withdrawing plunger head  1342  within tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . 
     For some applications, collection vial  50  is decoupled from filtration assembly  1324  by distally moving collection vial  50  with respect to tubular container  1330 , such as shown in  FIGS.  18 F and  19 F . 
     For some applications, the method further comprises sealing vial opening  52  with a collection vial cap after filter  60  has been advanced into collection vial  50 , such as shown in  FIGS.  18 G and  19 G . 
     For some applications, the method further comprises bathing filter  60  with liquid  1010  within collection vial  50  after filter  60  has been advanced into collection vial  50 , such as shown in  FIGS.  18 G and  19 G . For example, the liquid may be selected from the group consisting of: a lysis buffer, saline solution, and transport medium. 
     For some applications, the method further comprises, after filter  60  has been advanced into collection vial  50 , detecting the presence of a biological particulate trapped by filter  60 , such as described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G, and  6 A-G. 
     In some applications of the present invention (configuration not shown), a sampling device is provided that is similar in some respects to sampling device  1320 , and may implement any of the features thereof, mutatis mutandis. This sampling device, unlike sampling device  1320 , does not comprise plunger  1340 . This sampling device instead comprises a different liquid-pressure source. For example, the liquid-pressure source may comprise a positive-pressure pump (e.g., a hydraulic pump, a syringe, or a motorized and/or electrical pump) disposed upstream of filter  60 ; optionally, for some applications, the positive-pressure pump comprises a chamber with one or more flexible walls, the squeezing of which pumps liquid specimen sample  22  and/or air. 
     In an application of the present invention (not shown), the proximal portion of the shaft is axially movable with respect to the proximal container opening. 
     For some applications, the sampling device is configured to automatically axially move the shaft through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. 
     For some applications, the sampling device further comprises a spring, which is configured to axially move the proximal portion of the shaft with respect to the proximal container opening. 
     For some applications, the tubular container includes a distal tubular portion that is distal to the filter support and is configured to have an adjustable length. The sampling device is configured such that shortening of the adjustable length axially moves the shaft through the filter-support shaft-passage region, the plunger-head opening, and the vial opening. For example, the distal tubular portion may be axially collapsible to provide the shortening of the length of the distal tubular portion. 
     Reference is now made to  FIGS.  22 A-B , which are schematic illustrations of a sampling device  1420  for concentrating liquid specimen sample  22 , and a portion of the sampling device, respectively, in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  23 A-D , which are schematic illustrations of sampling device  1420  and a method of using sampling device  1420 , in accordance with respective applications of the present invention. 
     Reference is also made to  FIGS.  24 A-D , which are schematic cross-sectional illustrations of sampling device  1420  and the method of using sampling device  1420 , in accordance with respective applications of the present invention. 
     Reference is further made to  FIG.  25   , which is an enlarged schematic illustration of a portion of sampling device  1420  in the state shown in  FIGS.  23 D and  24 D , in accordance with an application of the present invention. 
     Sampling device  1420  typically comprises a filtration assembly  1424  and a collection vial  1450 , which may have any of the properties described hereinabove. Filtration assembly  1424  comprises a tubular container  1430 , a plunger  1440 , and filter  60 , which may have any of the properties described hereinabove with reference to  FIGS.  1 A- 9 B . Tubular container  1430  is shaped so as to define a proximal container opening  1432  for receiving liquid specimen sample  22 . Optionally, proximal container opening  1432  has any of the characteristics described hereinabove regarding the other proximal container openings described herein. Tubular container  1430  is also shaped so as to define an inner wall  1434 . 
     Collection vial  1450  typically is not shaped so as to define any pressure-release openings and does not comprise any pressure-release valves. 
     For some applications, filtration assembly  1424  comprises a plurality of filters (configuration not shown), optionally having any of the multi-filter configurations described hereinabove. Typically, tubular container  1430  may optionally have any of the characteristics, including, but not limited to, volume) of the tubular containers described hereinabove. For some applications, tubular container  1430  does not comprise a Luer lock or any other type of needle-coupling mechanism. 
     As labeled in  FIG.  24 A , plunger  1440  comprises a plunger head  1442 . Plunger  1440  is insertable into tubular container  1430  via proximal container opening  1432 , such that a lateral surface  1446  of plunger head  1442  forms a fluid-tight movable seal with inner wall  1434 . To this end, lateral surface  1446  may comprise an elastomeric material, such as natural rubber, synthetic rubber, a thermoplastic elastomer, or a combination thereof. 
     Collection vial  1450  is disengageably coupled to filtration assembly  1424 , such as described hereinbelow. Once collection vial  1450  has been decoupled from filtration assembly  1424 , a diagnostic test may be performed for the presence of particulate trapped by filter  60 , which is now in collection vial  1450 . For some applications, such as for transporting collection vial  1450  to a remote diagnostic laboratory, sampling device  1420  further comprises collection vial cap  80 , which is configured to seal vial opening  1452 , such as shown for collection vial  50  in  FIGS.  18 G and  19 G , mutatis mutandis. 
     Filtration assembly  1424  is configured such that movement (typically distal advancement) of plunger head  1442  within tubular container  1430 , when liquid specimen sample  22  is contained in tubular container  1430  and filter  60  is disposed in tubular container  1430 , pushes at least a portion of liquid specimen sample  22  through filter  60 . Filter  60  is configured to concentrate at least a portion of liquid specimen sample  22  onto filter  60 , while allowing filtrate  61  to pass through filter  60 . Typically, distal advancement of plunger  1440  within tubular container  1430  applies pressure to drive (e.g., push) at least a portion of liquid specimen sample  22  contained in tubular container  1430  through filter  60 , such as shown in the transitions between  FIGS.  23 A and  23 B  and between  FIGS.  24 A and  24 B . 
     Sampling device  1420  is configured such that filter  60  is advanceable into (e.g., entirely into) collection vial  1450  via vial opening  1452  while collection vial  1450  is disengageably coupled to filtration assembly  1424 , such as shown in  FIGS.  23 C and  24 C . 
     For some applications, sampling device  1420  is configured such that filter  60  is advanceable into collection vial  1450  via vial opening  1452  while plunger head  1442  is within tubular container  1430 , such as shown in  FIGS.  23 C and  24 C . For some of these applications, sampling device  1420  is configured such that filter  60  is advanceable into collection vial  1450  via vial opening  1452  while plunger head  1442  is advanced as far as possible within tubular container  1430 , such as shown in  FIGS.  23 C and  24 C . Alternatively or additionally, for some applications, sampling device  1420  is configured such that filter  60  is advanceable into collection vial  1450  via vial opening  1452  without any proximal withdrawal of plunger head  1442  within tubular container  1430 , such as shown in  FIGS.  23 C and  24 C . 
     For some applications, such as shown in  FIGS.  24 A-D , plunger  1440  comprises a plunger rod  1482 , which has a distal end portion  1484  to which plunger head  1442  is coupled. Plunger rod  1482  and plunger head  1442  may be fabricated as a single integral piece, or as two pieces fixed together during manufacture. Plunger  1440  has a proximal end  1481 . 
     For some of these applications, plunger rod  1482  is shaped so as to define an internal plunger space  1486 . For some of these applications, a proximal end  1488  of plunger rod  1482  is shaped so as to define a plunger-space proximal opening  1490  of internal plunger space  1486 . Plunger head  1442  is shaped so as to define a plunger-head opening  1444  through plunger head  1442  and into internal plunger space  1486 . 
     Typically, collection vial  1450  is removably disposed at least partially within internal plunger space  1486 . 
     Typically, collection vial  1450  is positioned proximal to plunger head  1442 . 
     For some of these applications, collection vial  1450  is removably disposed at least partially within internal plunger space  1486  while collection vial  1450  is an axially-compressed configuration, such as shown in  FIGS.  23 A-B  and  24 A-B. Collection vial  1450  is elongatable from the axially-compressed configuration, such as shown in the transitions between  FIG.  23 B  and  FIG.  23 C  and between  FIGS.  24 B and  24 C . Optionally, a wall  1413  of collection vial  1450  is accordion-shaped to allow the elongation. 
     Sampling device  1420  is typically configured such that filter  60  is removable from tubular container  1430  via plunger-space proximal opening  1490  while plunger head  1442  is within tubular container  1430  (filter  60  is also removable from tubular container  1430  via plunger-space proximal opening  1490  if plunger head  1442  has been removed from tubular container  1430 ). 
     Typically, filtration assembly  1424  further comprises a waste liquid receptacle  1456  for receiving filtrate  61 . For some of these applications, plunger rod  1482  is shaped so as to define therewithin waste liquid receptacle  1456 . Typically, waste liquid receptacle  1456  partially or entirely surrounds internal plunger space  1486 , such as shown. 
     Filtration assembly  1424  is configured such that movement of plunger head  1442  within tubular container  1430 , when liquid specimen sample  22  is contained in tubular container  1430  and filter  60  is disposed in tubular container  1430 , pushes at least a portion of liquid specimen sample  22  through filter  60  and filtrate-passage openings  1468  (described hereinbelow) and into waste liquid receptacle  1456 . 
     For some applications, waste liquid receptacle  1456  contains a disinfectant or a liquid-absorbing material. 
     Optionally, waste liquid receptacle  1456  is shaped so as to define an opening through an external wall of waste liquid receptacle  1456  to release displaced air, similar to opening  58  of waste liquid receptacle  56 , described hereinabove with reference to  FIGS.  2 A-G . For example, the opening may be located on a proximal portion of the external wall, typically above the highest level that filtrate  61  is expected to reach during ordinary use of the device. For some applications, waste liquid receptacle  1456  comprises an air filter (e.g., an N98 filter) that is disposed to filter air that passes out of waste liquid receptacle  1456  through the opening. Alternatively or additionally, for some applications, waste liquid receptacle  1456  comprises a one-way pressure-sensitive valve disposed in the opening. 
     For some applications, plunger head  1442  is shaped so as to define a filter support  1462 , which is shaped so as to define:
         a distal support surface  1459 , which may be perpendicular to a central longitudinal axis of plunger head  1442  (as shown), or may be angled with respect to the central longitudinal axis (configuration not shown),   a plurality of filtrate-passage openings  1468  through filter support  1462  into waste liquid receptacle  1456 , and   plunger-head opening  1444  (labeled in  FIGS.  24 C and  24 D ).       

     Filter  60  is (removably) disposed on distal support surface  1459 . 
     For some applications, sampling device  1420  comprises a filter-withdrawal shaft  1472 , which includes a distal portion  1408  (labeled in  FIG.  25   ) that is directly or indirectly coupled to filter  60 , typically via an end  1404  of collection vial  1450  opposite a vial opening  1452 . Filter-withdrawal shaft  1472  is disposed passing through internal plunger space  1486  (a portion or an entirety of filter-withdrawal shaft  1472  may be disposed within internal plunger space  1486 ). 
     Sampling device  1420  is typically configured such that proximal withdrawal of filter-withdrawal shaft  1472  out of internal plunger space  1486 , while plunger head  1442  is within tubular container  1430 , pulls filter  60  into internal plunger space  1486  via plunger-head opening  1444  and out of internal plunger space  1486  via plunger-space proximal opening  1490  (as shown in the transitions between  FIGS.  23 B and  23 C  and between  FIGS.  24 B and  24 C ), and removes filter-withdrawal shaft  1472  and filter  60  from filtration assembly  1424  (as shown in the transitions between  FIGS.  23 C and  23 D  and between  FIGS.  24 C and  24 D ). It is noted that filter-withdrawal shaft  1472  of sampling device  1420  is not an element of filtration assembly  1424 , but instead is removable therefrom, as shown in  FIGS.  23 D and  24 D . 
     For some applications, sampling device  1420  comprises a distal plate  1471  (labeled in  FIG.  24 A ), which is disposed in contact with a distal surface of filter  60 , and is directly or indirectly coupled to filter-withdrawal shaft  1472  through end  1404  of collection vial  1450 . For example, distal plate  1471  may be circular, i.e., shaped as a disc, or any other shape. Distal plate  1471  may be flexible, e.g., comprise silicone, or may be rigid, e.g., comprise metal or a polymer. 
     For some applications, plunger-space proximal opening  1490  and a longitudinal portion of filter-withdrawal shaft  1472  are shaped so as to define corresponding female and male screw threads  1423 A and  1423 B (labeled in  FIG.  24 D ), respectively, which (a) removably couple filter-withdrawal shaft  1472  to plunger rod  1482 , such as shown in  FIGS.  22 A,  23 A -B, and  24 A-B, while filter-withdrawal shaft  1472  is disposed passing through internal plunger space  1486 , and (b) prevent the premature proximal withdrawal of filter-withdrawal shaft  1472  out of internal plunger space  1486 . Sampling device  1420  is configured such that rotation of filter-withdrawal shaft  1472  and plunger-space proximal opening  1490  with respect to each other (a) causes an initial portion of the proximal withdrawal of filter-withdrawal shaft  1472  out of internal plunger space  1486 , such as shown in the transitions between  FIG.  23 B  and  FIG.  23 C  and between  FIG.  24 B  and  FIG.  24 C , and (b) decouples female and male screw threads  1423 A and  1423 B from each other, thereby allowing the continuation of the proximal withdrawal of filter-withdrawal shaft  1472  out of internal plunger space  1486 , such as shown in  FIGS.  23 C-D  and  24 C-D. 
     Optionally, in configurations in which plunger  1440  and tubular container  430  are threadingly coupled to each other, such as described hereinabove with reference to  FIG.  12   , (a) the threading between plunger-space proximal opening  1490  and filter-withdrawal shaft  1472  and (b) the threading between plunger  1440  and tubular container  430  have opposite handedness. 
     For other applications, plunger-space proximal opening  1490  and filter-withdrawal shaft  1472  are not threadingly coupled together. 
     As mentioned above, for some applications, collection vial  1450  is removably disposed at least partially within internal plunger space  1486  while collection vial  1450  is the axially-compressed configuration, such as shown in  FIGS.  23 A-B  and  24 A-B. Collection vial  1450  is elongatable from the axially-compressed configuration, such as shown in the transitions between  FIG.  23 B  and  FIG.  23 C  and between  FIGS.  24 B and  24 C . For these applications, sampling device  1420  is configured such that the proximal withdrawal of filter-withdrawal shaft  1472  out of internal plunger space  1486 , while plunger head  1442  is within tubular container  1430 , pulls filter  60  into collection vial  1450  and elongates collection vial  1450 . At least a portion of filter  60  is typically bunched up within collection vial  1450 , such as into a flower-like arrangement, from the filter&#39;s initial flat shape while disposed on the filter support. 
     For some applications, sampling device  1420  further comprises a shaft handle  1405 , which is coupled to a proximal portion of filter-withdrawal shaft  1472 . 
     For some applications, sampling device  1420  is configured such that collection vial  1450  is decouplable from filtration assembly  1424  while plunger head  1442  is within tubular container  1430 , such as shown in  FIGS.  23 D and  24 D . For some of these applications, sampling device  1420  is configured such that collection vial  1450  is decouplable from filtration assembly  1424  while plunger head  1442  is advanced as far as possible within tubular container  1430 , such as shown in  FIGS.  23 D and  24 D . Alternatively or additionally, for some applications, sampling device  1420  is configured such that collection vial  1450  is decouplable from filtration assembly  1424  without any proximal withdrawal of plunger head  1442  within tubular container  1430 , also such as shown in  FIGS.  23 D and  24 D . 
     For some applications, sterile packaging is provided, in which at least sampling device  1420  is removably disposed. 
     Reference is still made to  FIGS.  22 A- 25   . In some applications of the present invention, a method for concentrating liquid specimen sample  22  is provided. The method may optionally be practiced in combination with the method described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G,  6 A-G,  7 A-F, and  8 A-F, and/or the method described hereinabove with reference to  FIGS.  18 A-G  and  19 A-G. 
     The method comprises:
         placing liquid specimen sample  22  in tubular container  1430  of filtration assembly  1424 , such as shown in  FIGS.  23 A and  24 A ;   inserting plunger head  1442  of plunger  1440  into tubular container  1430  via proximal container opening  1432  of tubular container  1430 , such as shown in  FIGS.  23 B and  24 B ;   distally advancing plunger head  1442  within tubular container  1430  to drive at least a portion of liquid specimen sample  22  through filter  60  disposed in tubular container  1430 , such as shown in  FIGS.  23 B and  24 B  (it is noted that in this configuration, filter  60  is not initially disposed in tubular container  1430  when liquid specimen sample  22  is placed in tubular container  1430 , and is inserted into tubular container  1430  as plunger head  1442  is inserted into tubular container); and   removing filter  60  from tubular container  1430  via plunger-space proximal opening  1490  while plunger head  1442  is within tubular container  1430 , as shown in  FIGS.  23 C-D  and  24 C-D.       

     For some applications, liquid specimen sample  22  may be acquired and/or may have any of the characteristics described hereinabove. 
     For some applications, the method further comprises, after filter  60  has been removed from tubular container  1430 , detecting the presence of a biological particulate trapped by filter  60 , such as described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G, and  6 A-G. 
     For some applications in which sampling device  1420  comprises a filter-withdrawal shaft, the filter-withdrawal shaft is not pre-coupled to filter  60  (configuration not shown). Instead, the filter-withdrawal shaft is advanced within internal plunger space  1486  (and optionally inserted into plunger space  1486 ) and coupled to filter  60  after plunger  1440  has been inserted into tubular container  1430  (and optionally been moved within tubular container  1430  to push the at least a portion of liquid specimen  22  through filter  60 ). 
     Reference is now made to  FIGS.  26 A-B , which are schematic illustrations of a sampling device  1520 ,  1520 A for concentrating liquid specimen sample  22 , and a portion of the sampling device, respectively, in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  27 A-D , which are schematic illustrations of sampling device  1520 ,  1520 A and a method of using sampling device  1520 ,  1520 A, in accordance with respective applications of the present invention. 
     Reference is also made to  FIGS.  28 A-D , which are schematic cross-sectional illustrations of sampling device  1520 ,  1520 A and the method of using sampling device  1520 ,  1520 A, in accordance with respective applications of the present invention. 
     Reference is further made to  FIG.  29   , which is an enlarged schematic illustration of a portion of sampling device  1520 ,  1520 A in the state shown in  FIGS.  27 D and  28 D , in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  30 A-B , which are schematic illustrations of a sampling device  1520 ,  1520 B for concentrating liquid specimen sample  22 , and a portion of the sampling device, respectively, in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  31 A-D , which are schematic illustrations of sampling device  1520 ,  1520 B and a method of using sampling device  1520 ,  1520 B, in accordance with respective applications of the present invention. 
     Reference is also made to  FIGS.  32 A-D , which are schematic cross-sectional illustrations of sampling device  1520 ,  1520 B and the method of using sampling device  1520 ,  1520 B, in accordance with respective applications of the present invention. 
     Reference is further made to  FIG.  33   , which is an enlarged schematic illustration of a portion of sampling device  1520 ,  1520 B in the state shown in  FIGS.  31 D and  32 D , in accordance with an application of the present invention. 
     Sampling device  1520 A and sampling device  1520 B are two configurations of sampling device  1520 , and are identical other than as described hereinbelow. 
     Other than as described hereinbelow, sampling device  1520  is generally similar to sampling device  1420  described hereinabove with reference to  FIGS.  22 A- 25   , and may implement any of the features thereof, mutatis mutandis. Like reference numerals refer to like parts. 
     Sampling device  1520 A comprises a collection vial  1550 ,  1550 A and sampling device  1520 B comprises a collection vial  1550 ,  1550 B. Sampling device  1520 A comprises a filtration assembly  1524 ,  1524 A and sampling device  1520 B comprises a filtration assembly  1524 ,  1524 B. 
     Unlike in sampling device  1420 , in sampling device  1520 , when collection vial  1550  is initially disengageably coupled to filtration assembly  1524 , such as shown in  FIGS.  27 A-B ,  28 A-B,  31 A-B, and  32 A-B, collection vial  1550  does not define a distally-facing vial opening  1452 . 
     Collection vial  1550  comprises a flexible material and is removably disposed at least partially within an internal plunger space  1586  of a plunger  1540  while collection vial  1550  is an inverted configuration, in which the inverted collection vial  1550  defines a proximal vial opening  1507 , such as shown in  FIGS.  27 A-B ,  28 A-B,  31 A-B, and  32 A-B. 
     As labeled in  FIGS.  28 A and  32 A , plunger  1540  comprises a plunger head  1542  (labeled in  FIGS.  28 C and  32 C ) that is shaped so as to define a plunger-head opening  1544  through plunger head  1542  and into an internal plunger space  1586 . 
     For some applications, sampling device  1520  comprises a filter-withdrawal shaft  1572 , which is disposed partially within the inverted collection vial  1550  within internal plunger space  1586 . Filter-withdrawal shaft  1572  includes a distal portion  1508  that is directly or indirectly coupled to filter  60 , typically via an end  1504  of collection vial  1450  opposite a vial opening  1502 . Sampling device  1520  is configured such that proximal withdrawal of filter-withdrawal shaft  1572  out of internal plunger space  1586 , while plunger head  1542  is within tubular container  1430 :
         inverts the inverted collection vial  1550  to an uninverted configuration, as shown in the transitions between  FIG.  28 B  and  FIG.  28 C  and between  FIG.  32 B  and  FIG.  32 C ,   pulls filter  60  into collection vial  1550  via plunger-head opening  1544 , as shown in the transitions between  FIG.  28 B  and  FIG.  28 C  and between  FIG.  32 B  and  FIG.  32 C ; at least a portion of filter  60  is typically bunched up within collection vial  1550 , such as into a flower-like arrangement, from the filter&#39;s initial flat shape while disposed on the filter support,   pulls collection vial  1550  out of internal plunger space  1586  via plunger-space proximal opening  1590 , as shown in the transitions between  FIG.  28 C  and  FIG.  28 D  and between  FIG.  32 C  and  FIG.  32 D , and   removes filter-withdrawal shaft  1572  and filter  60  from filtration assembly  1524 , as shown in the transitions between  FIG.  28 C  and  FIG.  28 D  and between  FIG.  32 C  and  FIG.  32 D .       

     In the uninverted configuration, collection vial  1550  is shaped so as to define a vial opening  1502 . 
     Optionally, a longitudinal portion of filter-withdrawal shaft  1572  that passes through plunger-head opening  1544  is narrower than a more proximal portion of filter-withdrawal shaft  1572 . 
     Optionally, a portion  1515  of filter-withdrawal shaft  1572  is cylindrical (e.g., tubular) and has an outer diameter that is approximately equal to an inner diameter of the inverted collection vial  1550 , in order to help maintain the inverted collection vial  1550  in the inverted configuration, such as shown in  FIGS.  28 A-B , until withdrawal of filter-withdrawal shaft  1572  therefrom, such as shown in  FIG.  28 C . 
     It is noted that filter-withdrawal shaft  1572  of sampling device  1520  is not an element of filtration assembly  1524 , but instead is removable therefrom, as shown in  FIGS.  27 D,  28 D,  31 D, and  32 D . 
     Reference is now made to  FIGS.  26 A- 29   . Sampling device  1520 A is configured such that the inverted configuration of collection vial  1550 A is a single-inverted configuration. 
     Reference is now made to  FIGS.  30 A- 33   . Sampling device  1520 B is configured such that the inverted configuration of collection vial  1550 B is a double-inverted configuration, such as shown in  FIGS.  32 A-B . 
     Reference is again made to  FIGS.  26 A- 29  and  30 A- 33   . In some applications of the present invention, a method for concentrating liquid specimen sample  22  is provided. The method may optionally be practiced in combination with the method described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G,  6 A-G,  7 A-F, and  8 A-F, and/or the method described hereinabove with reference to  FIGS.  18 A-G  and  19 A-G. 
     The method comprises:
         placing liquid specimen sample  22  in tubular container  1430  of filtration assembly  1524 , such as shown in  FIGS.  27 A,  28 A,  31 A, and  32 A ;   inserting plunger head  1542  of plunger  1540  into tubular container  1430  via proximal container opening  1532  of tubular container  1430 , such as shown in  FIGS.  27 B,  28 B,  31 B, and  32 B ;   distally advancing plunger head  1542  within tubular container  1430  to drive at least a portion of liquid specimen sample  22  through filter  60  disposed in tubular container  1430 , such as shown in  FIGS.  27 B,  28 B,  31 B, and  32 B  (it is noted that in this configuration, filter  60  is not initially disposed in tubular container  1430  when liquid specimen sample  22  is placed in tubular container  1430 , and is inserted into tubular container  1430  as plunger head  1542  is inserted into tubular container); and   removing filter  60  from tubular container  1430  via plunger-space proximal opening  1590  while plunger head  1542  is within tubular container  1430 .       

     For some applications, filter  60  is removed from tubular container  1430  by proximally withdrawing filter-withdrawal shaft  1572  out of internal plunger space  1586 , while plunger head  1542  is within tubular container  1430 , so as to invert the inverted collection vial  1550  to an uninverted configuration (as shown in the transition between  FIG.  28 B  and  FIG.  28 C  and the transition between  FIGS.  32 B and  32 C ), to pull filter  60  into collection vial  1550  via plunger-head opening  1544  (as shown in the transition between 
       FIG.  28 B  and  FIG.  28 C  and the transition between  FIGS.  32 B and  32 C ), to pull collection vial  1550  out of internal plunger space  1586  via plunger-space proximal opening  1590  (as shown in the transition between  FIG.  28 C  and  FIG.  28 D  and the transition between  FIGS.  32 C and  32 D ), and to remove filter-withdrawal shaft  1572  and filter  60  from filtration assembly  1524  (as shown in the transition between  FIG.  28 C  and  FIG.  28 D  and the transition between  FIGS.  32 C and  32 D ). 
     For some applications, liquid specimen sample  22  may be acquired and/or may have any of the characteristics described hereinabove. 
     For some applications, the method further comprises, after filter  60  has been removed from tubular container  1430 , detecting the presence of a biological particulate trapped by filter  60 , such as described hereinabove with reference to  FIGS.  1 A-G ,  2 A-G, and  6 A-G. 
     Reference is now made to  FIGS.  34 A-B , which are schematic illustrations of a configuration of a portion of sampling device  1520 ,  1520 A, in accordance with an application of the present invention. Reference is also made to  FIGS.  35 A-B , which are schematic cross-sectional illustrations of the portion of sampling device  1520 ,  1520 A, in accordance with an application of the present invention. Although the following configuration is described with reference to sampling device  1520 ,  1520 A, described hereinabove with reference to  FIGS.  26 A- 29   , the configuration may also be implemented in sampling device  1520 ,  1520 B, described hereinabove with reference to  FIGS.  30 A- 33   , and in sampling device  1420 , described hereinabove with reference to  FIGS.  22 A- 25   , mutatis mutandis. 
     In this configuration, when collection vial  1550  is in the uninverted configuration, such as shown in  FIGS.  34 A-B  and  35 A-B, end  1504  of collection vial  1550  opposite vial opening  1502  comprises a vial interface  1506 A. Filter-withdrawal shaft  1572  comprises a shaft interface  1506 B. Vial interface  1506 A and shaft interface  1506 B are removably couplable together. 
     For some applications, vial threaded interface  1506 A and shaft threaded interface  1506 B are threaded, such as shown in  FIGS.  34 A-B  and  35 A-B. For some of these applications, vial threaded interface  1506 A and shaft threaded interface  1506 B are shaped so as to define male and female threads, respectively, such as shown. For other of these applications, vial threaded interface  1506 A and shaft threaded interface  1506 B are shaped so as to define female and male threads, respectively (configuration not shown). 
     Typically, after collection vial  1550  has been removed internal plunger space  1586  and has assumed the uninverted configuration shown in  FIGS.  34 A and  35 A , filter-withdrawal shaft  1572  is decoupled from collection vial  1550  by decoupling vial interface  1506 A and shaft interface  1506 B from each other. 
     Reference is now made to  FIGS.  36 A-B , which are schematic illustrations of a sampling device  1620  for concentrating liquid specimen sample  22 , and a portion of the sampling device, respectively, in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  37 A-D , which are schematic illustrations of sampling device  1620  and a method of using sampling device  1620 , in accordance with respective applications of the present invention. 
     Reference is also made to  FIGS.  38 A-D , which are schematic cross-sectional illustrations of sampling device  1620  and the method of using sampling device  1620 , in accordance with respective applications of the present invention. 
     Reference is further made to  FIG.  39   , which is an enlarged schematic illustration of a portion of sampling device  1620  in the state shown in  FIGS.  37 D and  38 D , in accordance with an application of the present invention. 
     Other than as described hereinbelow, sampling device  1620  is generally similar to sampling device  1420  described hereinabove with reference to  FIGS.  22 A- 25   , and may implement any of the features thereof, mutatis mutandis. Like reference numerals refer to like parts. 
     Sampling device  1620  comprises a filtration assembly  1624  and a collection vial  1650 , which may have any of the properties described hereinabove. However, unlike collection vial  1450 , described hereinabove with reference to  FIGS.  22 A- 25   , collection vial  1650  typically does not assume an axially-compressed configuration in which the vial is elongatable (in other words, collection vial  1650  typically has a fixed length, as in convention vials). In addition, unlike the invertible collection vials  1550  of sampling device  1520 , collection vial  1650  is typically not inverted during use in sampling device  1620 . 
     Filtration assembly  1624  comprises tubular container  1430 , a plunger  1640  (labeled in  FIG.  38 A ), and filter  60 , which may have any of the properties described hereinabove with reference to  FIGS.  1 A- 9 B . 
     Sampling device  1620  is typically configured such that filter  60  is removable from tubular container  1430  via a plunger-space proximal opening  1690  while a plunger head  1642  of plunger  1640  is within tubular container  1430  (filter  60  is also removable from tubular container  1430  via plunger-space proximal opening  1690  if plunger head  1642  has been removed from tubular container  1430 ). Plunger head  1642  is shaped so as to define a plunger-head opening  1644  through plunger head  1642  and into an internal plunger space  1686  of plunger  1640 . 
     Sampling device  1620  is configured such that filter  60  is advanceable into (e.g., entirely into) collection vial  1650  via a vial opening  1652  while collection vial  1650  is disengageably coupled to filtration assembly  1624 , such as shown in  FIGS.  37 C and  38 C . 
     For some applications, sampling device  1620  is configured such that filter  60  is advanceable into collection vial  1650  via vial opening  1652  while plunger head  1642  is within tubular container  1430 , such as shown in  FIGS.  37 C and  38 C . For some of these applications, sampling device  1620  is configured such that filter  60  is advanceable into collection vial  1650  via vial opening  1652  while plunger head  1642  is advanced as far as possible within tubular container  1430 , such as shown in  FIGS.  37 C and  38 C . Alternatively or additionally, for some applications, sampling device  1620  is configured such that filter  60  is advanceable into collection vial  1650  via vial opening  1652  without any proximal withdrawal of plunger head  1642  within tubular container  1430 , such as shown in  FIGS.  37 C and  38 C . 
     For some applications, sampling device  1620  comprises a filter-withdrawal shaft  1672 , which:
         is disposed partially within collection vial  1650  within an internal plunger space  1686 ,   includes a proximal portion  1687  that is slidably disposed passing through a shaft-passage hole  1605  through an end  1604  of collection vial  1650  opposite vial opening  1652  (labeled in  FIG.  39   ), and   includes a distal portion  1608  (labeled in  FIG.  39   ) that is directly or indirectly coupled to filter  60 .       

     Sampling device  1620  is configured such that proximal withdrawal of filter-withdrawal shaft  1672 , while plunger head  1642  is within tubular container  1430 , pulls filter  60  into collection vial  1650  via plunger-head opening  1644  via vial opening  1652  (as shown in the transitions between  FIGS.  37 B and  37 C  and between  FIGS.  38 B and  38 C ). At least a portion of filter  60  is typically bunched up within collection vial  1650 , such as into a flower-like arrangement, from the filter&#39;s initial flat shape while disposed on the filter support. 
     Typically, sampling device  1620  is configured such that further proximal withdrawal of filter-withdrawal shaft  1672  out of internal plunger space  1686 , while plunger head  1642  is within tubular container  1430 , pulls collection vial  1650  out of internal plunger space  1686  via plunger-space proximal opening  1690  (as shown in the transitions between  FIGS.  37 C and  37 D  and between  FIGS.  38 C and  38 D ). It is noted that filter-withdrawal shaft  1672  of sampling device  1620  is not an element of filtration assembly  1624 , but instead is removable therefrom, as shown in  FIGS.  37 D and  38 D . 
     For some applications, sampling device  1620  further comprises a seal  1614  that inhibits fluid leakage between proximal portion  1687  of filter-withdrawal shaft  1672  and shaft-passage hole  1605 . 
     Optionally, an inner portion of seal  1614  may snap into an external circumferential groove of proximal portion  1687  of filter-withdrawal shaft  1672  upon the proximal withdrawal of most or all of filter-withdrawal shaft  1672  from collection vial  1650 , such as shown in  FIG.  39   . 
     Reference is now made to  FIGS.  22 A- 25 ,  26 A- 33 , and  36 A- 39   . As described hereinabove with reference to these figures, respectively, filter-withdrawal shafts  1472 ,  1572 , and  1672 , include respective distal portions  1408 ,  1508 , and  1608  that are directly or indirectly coupled to filter  60 . Exemplary ways in which the distal portions of the filter-withdrawal shafts may be directly or indirectly coupled to the filter include, but are not limited to:
         the distal portion of the filter-withdrawal shaft may be directly coupled to the filter, such as shown in  FIG.  39    for filter-withdrawal shaft  1672 , e.g., by an adhesive and/or by distal plate  1471 , which may be fixed, e.g., pinned, to the distal end of the distal portion of the filter-withdrawal shaft; in these configurations, the distal portion of the filter-withdrawal shaft passes through the end of the collection vial opposite the vial opening; and   the distal portion of the filter-withdrawal shaft may be indirectly coupled to the filter, such as shown in  FIGS.  25 ,  29 , and  33   , e.g., by a rod  1479  (labeled in  FIGS.  25 ,  29 , and  33   ) that (a) is fixed to the distal end of the distal portion of the filter-withdrawal shaft and (b) passes through the end of the collection vial opposite the vial opening, and optionally further by an adhesive and/or by distal plate  1471  which may be integral with rod  1479  or fixed to rod  1479 .       

     It will be appreciated by persons skilled in the art who have read the present application that the distal portions of the filter-withdrawal shafts may be directly or indirectly coupled to the filter in additional ways, all of which are within the scope of the present invention. 
     Reference is now made to  FIGS.  40 A-B , which are schematic illustrations of a sampling device  1720  for concentrating liquid specimen sample  22 , and a portion of the sampling device, respectively, in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  41 A-E , which are schematic illustrations of sampling device  1720  and a method of using sampling device  1720 , in accordance with respective applications of the present invention. 
     Reference is also made to  FIGS.  42 A-E , which are schematic cross-sectional illustrations of sampling device  1720  and the method of using sampling device  1720 , in accordance with respective applications of the present invention. 
     Other than as described hereinbelow, sampling device  1720  is generally similar to sampling device  1420  described hereinabove with reference to  FIGS.  22 A- 25   , and may implement any of the features thereof, mutatis mutandis. Like reference numerals refer to like parts. 
     Similar to sampling device  1420 , sampling device  1720  typically comprises a filtration assembly  1724 , which may have any of the properties described hereinabove. Filtration assembly  1724  comprises tubular container  1430 , a plunger  1740 , and filter  60 , which may have any of the properties described hereinabove with reference to  FIGS.  1 A- 9 B . However, sampling device  1720  does not comprise a collection vial configured or disposed in a similar manner to collection vials  1450 ,  1550 ,  1550 A,  1550 B, and/or  1650 . Nevertheless, sampling device  1720  may optionally comprise an extraction tube  1718 , such as described hereinbelow with reference to  FIGS.  41 E and  42 E . 
     Plunger head  1742  is shaped so as to define a plunger-head opening  1744  through plunger head  1742  and into an internal plunger space  1786  of a plunger rod  1782 . A proximal end of plunger rod  1782  is shaped so as to define a plunger-space proximal opening  1790  of internal plunger space  1786 . 
     Sampling device  1720  comprises a filter-withdrawal shaft  1772 , which includes a distal portion  1708  (labeled in  FIG.  42 D ) that is directly or indirectly coupled to filter  60 , and which is disposed passing through internal plunger space  1786 . Exemplary ways in which distal portion  1708  of filter-withdrawal shaft  1772  may be directly or indirectly coupled to filter  60  include, but are not limited to:
         distal portion  1708  of filter-withdrawal shaft  1772  may be directly coupled to filter  60 , such as shown in  FIG.  39   , e.g., by an adhesive and/or by distal plate  1471 , which may be fixed, e.g., pinned, to the distal end of the distal portion of the filter-withdrawal shaft; and   distal portion  1708  of filter-withdrawal shaft  1772  may be indirectly coupled to filter  60 , such as shown in  FIGS.  25 ,  29 , and  33    for filter-withdrawal shafts  1472 ,  1572 , and  1672 , respectively, e.g., by a rod that is fixed to the distal end of the distal portion of the filter-withdrawal shaft and optionally further by an adhesive and/or by distal plate  1471  which may be integral with the rod or fixed to the rod.       

     It will be appreciated by persons skilled in the art who have read the present application that the distal portion of the filter-withdrawal shaft may be directly or indirectly coupled to the filter in additional ways, all of which are within the scope of the present invention. 
     Sampling device  1720  is configured such that proximal withdrawal of filter-withdrawal shaft  1772  out of internal plunger space  1786 , while plunger head  1742  is within tubular container  1430 , pulls filter  60  into internal plunger space  1786  via plunger-head opening  1744  and out of internal plunger space  1786  via plunger-space proximal opening  1790 , and removes filter-withdrawal shaft  1772  and filter  60  from filtration assembly  1724 . At least a portion of filter  60  is typically bunched up, such as into a flower-like arrangement, from the filter&#39;s initial flat shape while disposed on the filter support. 
     It is noted that filter-withdrawal shaft  1772  of sampling device  1720  is not an element of filtration assembly  1724 , but instead is removable therefrom, as shown in  FIGS.  41 D-E  and  42 D-E. 
     Typically, but not necessarily, after filter-withdrawal shaft  1772  and filter  60  have been removed from filtration assembly  1724 , filter  60  and at a portion of filter-withdrawal shaft  1772  are inserted into extraction tube  1718 , such as shown in  FIGS.  41 E and  42 E . As mentioned below, the bunching up of at least a portion of filter  60  may help facilitate this insertion; in some respects, the bunched-up filter may function somewhat analogously to a conventional swab. Reagents may also be placed in the extraction tube  1718 , before or after insertion of filter  60 , as known in the diagnostic testing arts. Optionally, extraction tube  1718  implements all or a portion of the techniques described hereinabove with reference to  FIGS.  16 A-C , mutatis mutandis. 
     For some applications, sampling device  1720  comprises a filter receptacle  1714  that is slidably coupled to a distal end portion of filter-withdrawal shaft  1772  and shaped so as to define a distal receptacle opening  1716 . Sampling device  1720  is configured such that the proximal withdrawal of filter-withdrawal shaft  1772  out of internal plunger space  1786 , while plunger head  1742  is within tubular container  1430 , pulls a portion of filter  60  into filter receptacle  1714  via distal receptacle opening  1716 . For example, the portion of filter  60  may include a central portion (as viewed when filter  60  is flat). This pulling of the portion of filter  60  into filter receptacle  1714  typically causes the remainder of filter  60  to become bunched up, such as into a flower-like arrangement, and be disposed at least partially outside filter receptacle  1714 , from the filter&#39;s initial flat shape while disposed on the filter support. The bunched-up filter may function somewhat analogously to a conventional swab, and, because of the reduced diameter because of the bunching up, may be readily inserted into extraction tube  1718 , such as described above and shown in  FIGS.  41 E and  42 E . 
     Reference is still made to  FIGS.  40 A- 42 E , and is further made to  FIGS.  43 A-E , which are schematic illustrations of a sampling device  1720 ,  1720 A and a method of using sampling device  1720 ,  1720 A, in accordance with respective applications of the present invention. Sampling device  1720 A is one implementation of sampling device  1720 , described hereinabove with reference to  FIGS.  40 A- 42 E . 
     Reference is additionally made to  FIGS.  44 A-B , which are schematic illustrations of a portion of a sampling device  1720 ,  1720 B and a method of using sampling device  1720 ,  1720 B, in accordance with respective applications of the present invention. Sampling device  1720 B is one implementation of sampling device  1720 , described hereinabove with reference to  FIGS.  40 A- 42 E . 
     Sampling device  1720 ,  1720 A,  1720 B further comprises an extraction-tube cap  1719 , which is disposed radially surrounding filter-withdrawal shaft  1772  along a first longitudinal portion  1773 A of filter-withdrawal shaft  1772 , such that a distal second longitudinal portion  1773 B of filter-withdrawal shaft  1772  is distal to extraction-tube cap  1719  (labeled in  FIGS.  43 B and  44 A ). Typically, extraction-tube cap  1719  has an outer diameter that is greater than an outer diameter of filter-withdrawal shaft  1772 . Extraction-tube cap  1719  and filter-withdrawal shaft  1772  may be integral with each other, or may comprise separate pieces that are coupled together, typically during manufacture. 
     Reference is still made to  FIGS.  43 A-E  and  44 A-B. For some applications, filter-withdrawal shaft  1772 ,  1772 A,  1772 B is shaped so as to define, proximal to extraction-tube cap  1719 , a proximal third longitudinal portion  1773 C that is configured to provide a predetermined separation border  1775  between proximal third longitudinal portion  1773 C and filter-withdrawal shaft  1772  distal to predetermined separation border  1775 . For these applications, a method of using sampling device  1720 ,  1720 A,  1720 B further comprises separating, at predetermined separation border  1775 , proximal third longitudinal portion  1773 C from filter-withdrawal shaft  1772 ,  1772 A,  1772 B distal to predetermined separation border  1775 , such as shown in the transition between  FIG.  43 C  and  FIG.  43 D . 
     For some applications, such as shown, proximal third longitudinal portion  1773 C is longitudinally connected to first longitudinal portion  1773 A of filter-withdrawal shaft  1772  by a fourth longitudinal portion  1773 D of filter-withdrawal shaft  1772  longitudinally between predetermined separation border  1775  and extraction-tube cap  1719 . For other applications, proximal third longitudinal portion  1773 C is directly longitudinally adjacent extraction-tube cap  1719  (configuration not shown). 
     For some applications, predetermined separation border  1775  is defined by one or more of the following features:
         a lesser cross-sectional area of filter-withdrawal shaft  1772  at predetermined separation border  1775  than longitudinally adjacent to predetermined separation border  1775 , such as shown in the figures,   scoring, such as shown in the figures,   perforation (configuration not shown),   corresponding male and female screw threads (configuration not shown), and/or   corresponding male and female tapered friction-fitting surfaces (configuration not shown).       

     For some applications, a method of using sampling device  1720  comprises separating, at predetermined separation border  1775 , proximal third longitudinal portion  1773 C from filter-withdrawal shaft  1772  distal to predetermined separation border  1775 . For applications in which predetermined separation border  1775  is defined by the lesser cross-sectional area of filter-withdrawal shaft  1772  at predetermined separation border  1775  than longitudinally adjacent to predetermined separation border  1775 , separating comprises breaking filter-withdrawal shaft  1772  at predetermined separation border  1775 . For applications in which predetermined separation border  1775  is defined by scoring or perforation, separating comprises breaking filter-withdrawal shaft  1772  at predetermined separation border  1775 . For applications in which predetermined separation border  1775  is defined by corresponding male and female screw threads, separating comprises unscrewing the male and the female screw threads from each other. For applications in which predetermined separation border  1775  is defined by corresponding male and female tapered friction-fitting surfaces, separating comprises separating the male and the female tapered friction-fitting surfaces from each other. 
     Reference is again made to  FIGS.  43 A-E . For some applications, filter-withdrawal shaft  1772 ,  1772 A is shaped so as to define an internal channel  1791  that passes longitudinally through first longitudinal portion  1773 A and has:
         one or more distal openings  1793  (e.g., lateral openings, as shown) distal to extraction-tube cap  1719 , and   a proximal opening  1795  that is disposed at predetermined separation border  1775  and that is open to outside filter-withdrawal shaft  1772  upon separation of proximal third longitudinal portion  1773 C at predetermined separation border  1775  (and is typically sealed to outside filter-withdrawal shaft  1772  before separation of proximal third longitudinal portion  1773 C at predetermined separation border  1775 ).       

     Reference is still made to  FIGS.  43 A-E . For some applications in which sampling device  1720 ,  1720 A further comprises extraction tube  1718  having a proximal end opening  1721 , filter-withdrawal shaft  1772 ,  1772 A, filter  60 , extraction tube  1718 , and extraction-tube cap  1719  are configured such that filter  60  and distal second longitudinal portion  1773 B of filter-withdrawal shaft  1772  are disposable within extraction tube  1718  via proximal end opening  1721  of extraction tube  1718 , such that extraction-tube cap  1719  seals at least a portion of extraction tube  1718  other than allowing fluid flow through internal channel  1791  via one or more distal openings  1793  and proximal opening  1795 . For these applications, a method of using sampling device  1720 ,  1720 A further comprises dripping a liquid through internal channel  1791  and out of proximal opening  1795 . For example, the liquid may comprise reagents in which filter  60  was inserted. For example, the liquid may be dripped onto a diagnostic test, such as onto a sample pad  1797  of a lateral flow immunoassay test strip  1799 . 
     For some applications (configuration not shown), filter-withdrawal shaft  1772 ,  1772 A is not shaped so as to define predetermined separation border  1775 . For some of these applications (configuration not shown), filter-withdrawal shaft  1772 ,  1772 A is shaped so as to define an internal channel that passes longitudinally through filter-withdrawal shaft  1772 ,  1772 A and is open at a proximal end of the filter-withdrawal shaft. Typically, the proximal opening of the internal channel is sealed by a removable plug. 
     Reference is made to  FIGS.  44 A-B . For some applications in which sampling device  1720  further comprises extraction tube  1718  having proximal end opening  1721 , filter-withdrawal shaft  1772 B, filter  60 , extraction tube  1718 , and extraction-tube cap  1719  are configured such that filter  60  and distal second longitudinal portion  1773 B of filter-withdrawal shaft  1772  are disposable within extraction tube  1718  via proximal end opening  1721  of extraction tube  1718 , such that extraction-tube cap  1719  seals at least a portion of extraction tube  1718 . Optionally, extraction tube  1718  comprises a screw-off distal tip cap  1749  that removably seals a distal end  1751  of extraction tube  1718  opposite proximal end opening  1721 . Upon removal of distal tip cap  1749 , liquid can be dripped out of extraction tube  1718  via an opening through distal end  1751 . 
     Reference is now made to  FIGS.  45 A-B , which are schematic illustrations of a distal portion of plunger head  1442 , in accordance with an application of the present invention. The features of this configuration may also be implemented in plunger heads  1542 ,  1642 , and/or  1742 , mutatis mutandis, described herein with reference to  FIGS.  26 A- 33 ,  36 A- 39   , and  40 A- 44 B, respectively. In this configuration, plunger head  1442  further comprises one or more one-way valves  1431  that are configured to provide one-way flow through filtrate-passage openings  1468  into waste liquid receptacle  1456 . For example, one-way valves  1431  may comprise flaps. Pressure generated distal to one-way valves  1431  by distal advancement of plunger head  1442  opens the valve and allows filtrate  61  to pass into waste liquid receptacle  1456 . 
     In an embodiment, the techniques and apparatus described herein are combined with techniques and apparatus described in one or more of the following patent applications, which are assigned to the assignee of the present application and are incorporated herein by reference:
     PCT Publication WO 2018/158768 to Fruchter et al., and US Patent Application Publication 2019/0381498 in the national stage thereof;   U.S. Provisional Application 62/727,208, filed Sep. 5, 2018;   U.S. Provisional Application 62/727,268, filed Sep. 5, 2018;   PCT Publication WO 2020/049566 to Fruchter et al.;   PCT Publication WO 2020/049569 to Fruchter et al., and US Patent Application Publication 2021/0215585 in the national stage thereof;   U.S. Provisional Application 62/896,295, filed Sep. 5, 2019;   U.S. Provisional Application 62/988,145, filed Mar. 11, 2020;   U.S. Provisional Application 62/988,259, filed Mar. 11, 2020;   U.S. Provisional Applications 63/020,723, filed May 6, 2020; 63/037,707, filed Jun. 11, 2020; 63/067,535, filed Aug. 19, 2020; 63/117,294, filed Nov. 23, 2020; 63/156,843, filed Mar. 4, 2021; 63/158,005, filed Mar. 8, 2021; 63/166,378, filed Mar. 26, 2021; and 63/176,565, filed Apr. 19, 2021;   U.S. Provisional Application 63/071,529, filed Aug. 28, 2020;   International Application PCT/IL2020/050957, filed Sep. 3, 2020, which published as PCT Publication WO 2021/044417 to Holtz et al.;   US Patent Application Publication 2021/0102876 to Fruchter et al.;   PCT Publication WO 2021/181339 to Feldman et al.;   PCT Publication WO 2021/181338 to Fruchter et al.;   PCT Publication WO 2021/224925 to Levitz et al.;   International Application PCT/IL2021/051035, filed Aug. 24, 2021, which published as WO 2022/044002 to Levitz et al.; and/or   U.S. Provisional Application 63/134,282, filed Jan. 6, 2021.   

     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.