Patent Publication Number: US-11655445-B2

Title: Surface detection and picktool manipulator

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 16/699,884, filed Dec. 2, 2019, allowed, which application is a continuation of U.S. patent application Ser. No. 15/560,048 which was filed on Sep. 20, 2017, now U.S. Pat. No. 10,557,113, issued Feb. 11, 2020. U.S. patent application Ser. No. 15/560,048 is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/EP2016/056910 filed Mar. 30, 2016, published in English, which claims priority from the benefit of the filing date of U.S. Provisional Application No. 62/140,002, filed Mar. 30, 2015, entitled SURFACE DETECTION AND PICKTOOL MANIPULATOR all of which are the disclosure of which is hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter of the present application relates to robotic manipulator equipment and methods of operating the same. In one example, robotic manipulator equipment may be used for collection of a specimen from a culture medium such as an agar plate. 
     For collecting a specimen using a robotic system, e.g., for collecting a specimen of a microbial or bacterial culture from a viscous culture medium such as, for example, an agar plate, it is necessary that the robotic system accurately positions itself for collection of the specimen. Position of the culture in a horizontal plane (e.g., the positions in x and y horizontal directions in a Cartesian coordinate space) can be determined through calculations based on an imaging system. However, such imaging system cannot determine the vertical position of the culture with enough accuracy. The vertical position can be difficult to determine with an imaging system because the specimen and the medium may each vary greatly in characteristics such as, but not limited to, color, transparency, reflectance and moisture content. 
     Several methods have been proposed and investigated but no suitable solution has been found so far. Determining the vertical position of the specimen is essential because moving the robotic system too deep relative to the surface of the medium might cause the system to collect too much material of the culture medium, or collect too little of the specimen, e.g., collect too few bacteria. In either case, these problems can lead to erratic measurements and unreliable test results. 
     In view of these problems, further improvements in robotic collection systems and methods therefor are needed. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the disclosed embodiments, described herein is a device for collecting a specimen from a culture medium. The device includes a body portion that will receive a disposable picktool. As such the body portion is configured to receive the picktool, which is easily separated from the body portion after use. The body and picktool assembly are in approximately axial alignment in the described embodiment. The device includes a detector that generates a signal in response to a force applied to the picktool when the picktool is brought into contact with either the culture medium or a specimen disposed on the culture medium. 
     The device is configured to operate in at least first and second modes. In the first mode, the body and picktool assembly move relatively freely in the axial direction. This direction is roughly perpendicular to the surface of the culture medium. The second mode applies more resistance to the axial movement of the body and picktool assembly than when the device is in the first mode. 
     The picktool is configured to operate over a predetermined range of motion. In one embodiment, the resistance to movement in the axial direction when in the second mode progressively increases with displacement of the body beyond the predetermined range of motion. In further embodiments, the amount of the resistance to movement in the second mode increases as a step function upon displacement of the body beyond the first predetermined range of motion. 
     In some embodiments the device has a spring configured to begin to resist axial movement of the body in response to movement of the body at or following contact between the picktool and a specimen disposed on the culture medium when the device switches to the second mode. For example, the device is configured to switch from the first mode to the second mode when the picktool is in contact with or comes into contact with the specimen disposed on the culture medium. 
     In some embodiments the detector is configured to generate a signal in response to detecting a relative position between the device and the specimen. 
     In order to switch from the first mode to the second mode, the body comprises a structure coupled to the body. The body moves more freely in the axial direction relative to the structure in the first mode and the body is either more resistant or locked from such axial movement in the axial direction in the second mode. For example, a key is provided coupled to the body. The key cooperates with an opening in the structure above the key so that the key does not engage and may advance into and through the structure in the first mode. However, in the second mode the key cannot advance into and through the structure. In further embodiments the structure includes a motor coupled to the body for rotating the body in a direction about the axis. In these embodiments the motor is configured to rotate the body relative to the structure between the first position corresponding to the first mode in which the key can advance into and through the structure and the second position corresponding to the second mode in which the key cannot advance into and through the structure. In other further embodiments the key has at least one lateral extension away from an axis common to the key and body. The structure has an opening sized to permit the at least one extension to pass there through. 
     In other embodiments the structure has a sleeve through which the body extends. When the device is operating in the first mode in these embodiments the body is freely moveable in the axial direction within the sleeve and the sleeve restrains the body in coaxial arrangement therewith. When operating in the second mode the sleeve and structure cooperate to restrain movement of the body relative to the structure. 
     In alternative embodiments the device that collects the specimen from the culture medium has a body that receives and retains a removable picktool. The picktool extends from the device when received by the body. The device has a mechanism for moving the body (which can be coupled with the picktool) in Cartesian space. Therefore, the picktool can be moved from a first location where it is received by the device to a second location where it is used to pick a specimen disposed on a culture medium. The device includes a mechanism that advances the picktool to the specimen. The device also includes a signal generator that generates a signal when the picktool is advanced into contact with the specimen disposed on the culture medium. The device includes a mechanism that allows the body to move more freely in a direction proximately perpendicular to the surface of the culture medium within a predetermined range of motion in a first mode. The mechanism, when switched to a second mode, increases the resistance of the body to movement in the proximately perpendicular direction when the body travels beyond the predetermined range of motion in a second mode. In certain embodiments the body moves freely in the about perpendicular direction (with respect to the culture media) in the first mode and does not move in the about perpendicular direction in the second mode. 
     According to another aspect of the disclosure, a method for collecting a specimen from a culture medium is disclosed. The method may include initiating a first mode of a device for collecting a specimen from a culture medium, the first mode permitting movement of the device in an axial direction relative to a support structure of the device; moving the device in the axial direction to receive and retain a picktool configured to collect the specimen; moving the picktool, by the device, into contact with the specimen disposed on the culture medium; initiating a second mode of the device and precluding movement of the device in the axial direction; manipulating the picktool while the picktool is attached to the device to collect the specimen; and depositing the collected specimen at a collection location. 
     In one embodiment of this aspect, the step of manipulating may include the device rotating the picktool. The picktool can additionally or alternatively be released from the device so as to discard the picktool. 
     In some embodiments, after depositing the collected specimen, the collected specimen may be processed. The step of processing may include at least one of the processes selected from the group comprising processing testing, culturing, or preserving. 
     In another embodiment, the method can further include detecting contact between the picktool and the culture medium. Additionally or alternatively, the method may include detecting a height at which the picktool contacts the culture movement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating movement of a device used in collecting a specimen from a medium in accordance with an embodiment of the invention. 
         FIG.  2    is a flowchart illustrating a method of detecting a height of contact with a medium and collecting a specimen from the medium in accordance with an embodiment of the invention. 
         FIG.  3    is a sectional view schematically illustrating a structure of an exemplary device for collecting a specimen from a medium in accordance with an embodiment of the invention. 
         FIG.  4 A  is a plan view schematically illustrating a device in a first position for operation in a first mode. 
         FIG.  4 B  is a plan view schematically illustrating a device in a second position for operation in a second mode. 
         FIG.  5    a sectional view illustrating a variation of the embodiment shown in  FIG.  3   . 
         FIG.  6    a sectional view illustrating a variation of the embodiment shown in  FIG.  3   . 
         FIG.  7    a sectional view illustrating a variation of the embodiment shown in  FIG.  3   . 
         FIG.  8    a sectional view illustrating a variation of the embodiment shown in  FIG.  3   . 
         FIG.  9    a sectional view illustrating a variation of the embodiment shown in  FIG.  3   . 
         FIG.  10    a sectional view illustrating a variation of the embodiment shown in  FIG.  3   . 
     
    
    
     DETAILED DESCRIPTION 
     Accordingly, a device provided herein that may be used both to detect a surface of a medium such as a surface of a specimen thereon, e.g., bacterial colony on a surface of a culture medium, e.g., an agar plate. Such device, which may also function as a rotational manipulator, and may include sensors, may also fulfill additional required functions such as detecting the presence of a replaceable picktool and receiving an unused picktool, depositing a collected specimen after collecting it, and assisting in the removal of the used picktool. 
     Accordingly, an improved device and method is provided for handling a picktool such as used in collecting a specimen from a medium, for example, a culture or tissue growing or otherwise supported on a medium, e.g., an agar plate. With such device, the height of the picktool relative to the medium can be accurately gauged using a signal generated by the device in response to the device moving the picktool into contact with the medium. 
     Thus, in one embodiment, the device can have a picktool-receiving body that receives and retains the picktool. The device may have a first mode of operation in which the body (and the picktool received thereby) moves more freely in axial directions of the body relative to a support structure of the device, such movement occurring in response to the picktool coming in contact with a medium or “engaging” the medium. When the device is moved towards the medium, typically in a downward direction or a direction that includes a substantial downward component, the picktool approaches the medium and contacts the medium while the device is moving toward the medium. As a result of such motion, the medium provides resistance to the downward motion of the picktool and the picktool-receiving body in an axial direction of the body away from the medium relative to other structure of the device, such as a support of the device. Thus, in one example, movement of the device downwardly towards the medium so that the picktool engages the medium causes the picktool and the picktool-receiving body to be urged in the axial direction, e.g., upwardly away from the medium relative to the other structure of the device. 
     Based on the axial movement of the body relative to the device&#39;s structure, a detector associated with the device generates a signal which can be used to determine a height of the device at which the picktool contacts the medium. The determined height is a vertical position of the device at which the device is positioned correctly for manipulating the picktool to collect a specimen from the medium. The device can then be used to collect a specimen from the culture medium. In particular examples, as described relative to  FIGS.  5 - 10    below, the device may have structure which applies increased downforce (or increased resistance to the upward force) between the picktool and the medium to assist in the collection of the specimen from the medium. 
     In one embodiment, when the device reaches the previously determined height for collecting a specimen, the body is restrained from being pushed upward relative to the device structure. The device can then manipulate the picktool to collect a specimen from the medium, such as by rotating the picktool, for example, using a motor. For example, the picktool can be moved by the device relative to the medium so as to gather material of the specimen from the culture medium. In a specific example, a motor coupled to the body can rotate the picktool relative to the medium, to cause the picktool to gather specimen material from the medium. In a particular example, the material gathered from the specimen lodges on a blade or other collecting surface of the picktool. 
     In a second mode of operation, rather than permitting the picktool receiving body to move freely, the picktool-receiving body is restrained from or precluded from moving axially relative to the device structure. In one example of operation in this mode, the device can be operated in this second mode when receiving a new picktool or discarding a used picktool. 
     Referring now to  FIGS.  1  and  2   , an example is provided of using the device in an automated method to collect individual specimens at a high repetition rate suitable for use in a high volume apparatus for sample collection from an inventory of culture plates. The media can vary from plate to plate and the number and type of media can vary widely. There may be one or more picks per plate. After collecting a specimen using a picktool retained by the device, the device deposits the collected specimen at a collection location for further processing, e.g. testing, further culturing, or preservation of the specimen. Thereafter, the device can discard the used picktool and then begin the same collection process again with the receiving of another picktool, and then collecting another specimen by a method as described above either from the same plate or a different plate as required by the system. 
     Thus, in an exemplary method of operation using the device  100 , a quantity of picktools  102  may be arranged in an array at a first station A ( FIG.  1   ) awaiting use. In one example, an external actuator  110  can move the device  100  in multiple degrees of freedom within a coordinate space. For example, the actuator may be programmed to automatically move the device in horizontal, vertical and/or circumferential directions between stations at which various work is performed. In this way, the actuator can move the device in at least lateral directions from station to station (e.g. the first station to collect a pick tool; second station to pick the sample; third station to deposit the picked sample, etc.), and move the device in upward and downward directions when needed. The actuator is controlled electronically by components such as logic circuitry, a set of instructions executable by a processor, or both logic circuitry and a set of executable instructions. In a particular example, the actuator is controlled by one or more programs containing instructions executed by one or more processors. 
     Thus, as seen at A ( FIG.  1   ) and  210  ( FIG.  2   ), the device can be operated in the second mode of operation which restrains or resists or dampens upward movement of the body for carrying the picktool, and the actuator may move the device in an axial direction of the picktool-receiving body such that the body receives a picktool. For example, the device can be moved downwardly such that a shaft of the picktool is received within a cavity of the body and is firmly retained to preclude relative movement between the picktool shaft and the body. 
     Thereafter, the device can be put in the first operational mode which permits the body to move more freely relative to the device. Then, as seen at B ( FIG.  1   ) and  220  ( FIG.  2   ), the actuator may move the device in a direction, e.g., downwardly, towards a medium while the device is operated in a first mode to determine a height at which the picktool contacts the medium. The device continues to move downward so long as contact between the picktool and the sample has not yet been detected, as seen at  230  ( FIG.  2   ). The height is determined at which a detector of the device detects contact between the picktool and the culture medium. In one example, contact is detected by detecting resistance to movement in the downward direction which translates to movement of the picktool in the upward direction. 
     Then, as seen at C ( FIG.  1   ) and  250  ( FIG.  2   ), with the device still in the first mode of operation the picktool contacts the specimen disposed on the medium at which time the device switches from the first mode to the second mode to collect the specimen. When collecting the specimen, the device at least resists or dampens upward motion but may, in alternative embodiments, apply increased downward force to the picktool to cause the picktool to remain in firm contact with the culture medium and the specimen as collection occurs. Various ways of applying and maintaining downward force between the picktool and the medium are described below with respect to  FIGS.  6 - 10   , for example. Then, as seen at D ( FIG.  1   ) and  260  ( FIG.  2   ), the actuator can then cause the device to retract the picktool from the specimen surface (the picktool should move vertically upward initially to avoid dragging the picktool across the plate surface) and then move the device to a specimen deposit location, e.g., a sample preparation station, and then cause the collected specimen to be released from the picktool into a solution for further processing. 
     Afterwards, at E ( FIG.  1   ) the device  100  can be put in the second operational mode and moved to a third station, at which time the device can then discard the used picktool. The process then can start again by causing the device to collect another (unused) picktool at A. The picktool is collected by the device as described above. 
     Referring now to  FIG.  3   , a specific example will now be provided of a device  300  in accordance with an embodiment of the invention. As illustrated in the  FIG.  3    embodiment, device  300  has a picktool-receiving body  302  having a cavity  305  therein for receiving a portion of a picktool  102  ( FIG.  1   ) which can be a shaft of the picktool. One skilled in the art is aware of many different configurations in which the device might be configured to receive a picktool. The invention is not to be construed as limited to the specific configuration illustrated in  FIG.  3   . The cavity  305  defines an axis  306  extending in an axial direction, in which direction the picktool shaft extends when received in the cavity  305 . As received in the cavity  305 , the picktool is firmly retained by the body  302  so as to preclude movement relative to the body except at times when the shaft of the picktool is being inserted into the body  302  or being removed or jettisoned therefrom. 
     The cross-sectional dimension and shape of the cavity  305  typically match the dimension and shape of the shaft of the picktool, but in some cases the dimensions and shapes need only correspond to the extent that the picktool when received is firmly retained in the cavity  305 . A rod  304  can be slidably disposed within the body  302 , the rod having, for example, a fixed knob  326  which can be forced upward when a picktool is inserted into the open end  301  of the body  302 . The rod  304  may be biased to project downwardly to the open end  301  when a picktool is not inserted into the body  302 . 
     As further seen in  FIG.  3   , an optical reflective sensor  328  may be provided for detecting when the knob  326  is pushed upward, so as to detect the presence of a picktool received by the body  302 . 
     The body  302  may have a threaded hole at a top thereof for mounting a head  308 , such as with a screw  309 , for example. The body  302  may have a groove  312 , typically having a V-shape, in which a bead or ball  314  may be situated and permitted to roll. A sleeve  316  may have a corresponding hole so that the ball is retained between the sleeve and the body  302 . 
     In one example, the sleeve  316  can be press fitted into an opening of a hollow rotor  318  of a motor, such as a stepper motor of the device in which elements  320  represent further portions, e.g., a housing and stator of the motor. The sleeve  316  and picktool receiving body  302  cooperate together to allow the body  302  to move freely in an axial direction, e.g., vertically, which is a direction away from the open end  301  of the body, while locking the body to the rotor  318  of the motor, such that the body  302  can be controllably rotated between various positions by rotating the rotor. 
     The head  308 , attached at a top end  322  of the body  302  which is remote from the open end  301 , may have one or more portions extending in a lateral direction away from the axis  306 . As depicted in  FIG.  3   , the laterally extending portions may be two wings  324  which extend in opposite directions away from the axis  306 . As further shown in plan view in  FIG.  4 A  (looking upward from beneath device structure  340 ), in the first mode of operation, in a first position, the wings  324  can be aligned with a corresponding opening  325  in the device structure, e.g., a top cover of the device. In this first mode, the alignment of the wings with the opening allows the wings  324  to move freely in the axial direction of the body  302 , e.g., upwardly and downwardly. By contrast, in the second mode of operation the head  308  and wings  324  extending therefrom are positioned so that the wings are not aligned with the opening  325 , as seen at  FIG.  4 B . For example, in the second position the head may be rotated to an angle of 90° relative to the first position, such that structure of the device restrains the head  308  and the body  302  attached thereto from moving in the axial directions. 
     Although the head  308  with wings  324  and opening  325  in  FIG.  3    are depicted as a ‘keyhole’ arrangement, other arrangements are possible which serve the function equally well. For example, instead of the opening having a cylindrical portion and side portions extending in opposite directions away from the axis  306 , the opening may alternatively have the shape of a simple rectangle sufficient to accommodate the wings in the first position, while in the second opening the wings are blocked from moving in the axial direction by the area of the structure lying outside of such rectangular opening. 
     The device may include a detector  330  for generating a signal in response to the picktool contacting the culture medium. In one example, the detector may detect movement of the head in the axial, e.g., upward direction such as when the device moves downwardly towards a medium and the picktool then contacts the medium. Such detector  330  then generates a signal when the body is thrust upward upon contact with the culture medium in a state in which the head  308  and body  302  of the device are in the first position that permits the body to freely move in the axial direction. In one example, the detector may be a Hall effect sensor  330  that is configured to generate an electrical signal in response to a change in magnetic field, such as due to movement of a magnet  332  disposed in or on the head  308 . In one example, the head  308  may incorporate four magnets  332  at a periphery of the head, each magnet spaced apart from the next adjacent magnet on the head by a 90 degree angle, wherein the magnetic polarization of the magnet at each position on the head alternates relative to the magnetic polarizations of the magnets adjacent to such magnet at the periphery of the head. The detector and such four magnet arrangement can be used to detect whether the head is aligned with the opening in the first position, or whether the head is in a second position that is rotated about the axis  306  relative to the first position such that the head is then restrained from moving axially. When the head is in a known position, the detector or Hall effect sensor  330  can be used to detect a vertical movement of the head away from the known position. 
     In an example of operation, when the head  308  is restrained from moving axially by device structure  340 , the device  300  can be moved in a downwardly direction by an external actuator ( 110 ;  FIG.  1   ) onto the shaft of the picktool  102  to receive the picktool within the body. Downward movement of the device can be continued until the picktool has been inserted to a predetermined position in the body or until the optical sensor  328  detects the knob  326 . 
     Then the device  300  can be moved upwardly by the actuator  110  and the rotor  318  of the stepper motor can be actuated so as to rotate the body through an angle of 90 degrees. At such time, the device is now in a first mode with the head  308  in a first position allowing unblocked vertical movement. The device  300  then is positioned above a surface of the medium containing the specimen (e.g., without limitation a microbial or bacterial colony on a growth medium such as agar), and then moved downward slowly until the detector  330  generates a signal based on the upward movement of the head  308 . The actual position of the vertical actuator at the time the signal is generated can be used to determine a height of the device relative to the medium at which the specimen lies on the medium. The picktool may now rest on the specimen, for example, a bacterial colony on a culture medium such as an agar medium, with a downward force which depends on the weight of those components associated with the portions of the device that move axially relative to the other portions of the device (e.g. body  302 , rod  304 , etc.). 
     In a particular embodiment, when operating the device in the first mode to detect a surface of the medium, if the total surface pressure of the picktool on the medium is too high (such as due to the combined weight of the device portions bearing down thereon), a magnet coupled with the body  302  can be positioned in a coil. In this way, when the coil is energized, the coil generates a magnetic field which acts on the magnet to create a force that can dampen the pressure of the picktool on the surface of the culture medium. 
     Functions and features of the above-described device can be implemented in a variety of ways. For example, as seen in  FIG.  5   , alternatively, or in in addition to the sensor  328  ( FIG.  3   ), the device may include an optoelectronic sensor  510  associated with a front surface  500  of the device. The sensor  510  may be configured as a reflective sensor for receiving light reflected from the picktool or from a surface of the culture medium. In one embodiment, the sensor  510  is configured to emit light in a direction towards the picktool and a signal based on a proportion of the emitted light is reflected from a surface of the picktool back on to the sensor. In a particular embodiment, the sensor may be U-shaped. The sensor is positioned so that it can detect the position of the picktool relative to the position of the body  302 . 
     In one embodiment, the device may include an inductive sensor  610  for detecting movement and/or presence of a metal part into proximity with the inductive sensor. For example, the inductive sensor  610  has a structure with which a part  620  (the upper portion of rod  304 ) associated with the body moves into proximity in response to upward movement of the body  302  when the picktool contacts the surface of the culture medium. In such embodiment, the part  620  is electrically conductive and typically made of metal to permit detection by the inductive sensor  610 . In one embodiment the inductive sensor has an annular structure and ‘knob’  326  ( FIG.  3   ) is omitted or sized to fit within the opening in the inductive sensor. In a variation of such embodiment, the inductive sensor may be provided as one or more inductive coils. 
     Alternatively, in one embodiment, the device may include one or more capacitive sensors which are capable of detecting presence of either metal or non-metal parts. The one or more capacitive sensors can be provided in place of inductive sensor  610 . In such embodiment, the capacitive sensor can detect the presence of or movement of a part  620  of the device, whether or not the part  620  is made of metal. In this embodiment, the sensor is a variable capacitor, capacitance varying with the position of the rod. A change in capacitance will indicate upward force caused by contact of the picktool with the specimen, for example. 
     Particular embodiments of the device can include structure configured to increase downforce between the picktool and the culture medium, such as for when the picktool is in contact with the culture medium for collecting a specimen. For example,  FIG.  7    depicts an inductive coil  710  which can be used in conjunction with one or more magnets  712  or magnetic portions of the body  302 . The magnetic coil can be configured to add resistance to the axial motion of the body  302  or repel the body  302  in the axial direction. In the second instance, the coil may be energized with a first applied current to apply a magnetic attractive force to the magnets  712  to cause the magnets to be attracted towards the coil  710  and apply a downward force to the body  302  to move the body downwards. When the coil is energized at a lower current level or is not energized, the coil applies less force to the body  302  and the body may then move upwards with less or no resistance. The device may additionally include a restoring element, which may be, for example, a spring ( 802 ;  FIG.  8   ), the restoring element configured to restore a position of the body  302  to a resting position when the coil is energized at a lower level or when the coil is not energized. 
     In one embodiment, the coil may be configured to be energized with current of opposite polarity from the first applied current. In this case, the coil applies a magnetic repulsive force to the magnets  712  to cause the magnets to be repulsed away from the coil  710  to apply an upward force to the body  302 . 
       FIG.  8    illustrates an embodiment which includes a spring  802  for providing a restoring force to the body  302 . In the illustrated embodiment the spring is disposed above the body providing increased resistance to the body moving upwards. In one example, the spring  802  has a first end  804  mechanically coupled with the body  302  such as through screw  309  with screwhead  310 , and a second end  806  abutting a part of the device having a fixed position. In operation, movement of the body  302  in the upward direction compresses the spring  802 , such that the spring applies increased downforce on the body  302  which downforce increases the more the body moves upward. In such way, the device applies an increased force between the picktool and the culture medium when the picktool is forced into contact with the culture medium. 
     In one embodiment as seen in  FIG.  9   , the device may include one or more weights  910  which are arranged to apply an increased downward gravitational force on the body  302  after the body has moved a predetermined upward distance from a resting position of the body  302 . For example, an annular weight  910  can be positioned so as to rest partly on a ledge (not shown) on or within the device. When the device is moved by the actuator downwardly towards the culture medium, the body  302  moves upward upon contact with the culture medium, such that an element, e.g., screwhead  310  coupled with the body, eventually comes into contact with the weight  910 . If the body remains at the same position or continues to move upwardly, the weight  910  is now coupled with the body  302  so as to apply a downward gravitational force through the body  302  to the culture medium. 
     In another embodiment as seen in  FIG.  10   , pressurized air or gas within a sealed chamber  1004  can apply downforce to the body  302  when the body is moved into contact with a culture medium. Thus, when the device is moved by the actuator downwardly towards the culture medium, the body  302  moves upward upon contact with the culture medium, such that an element (knob  326 ) moving within the chamber  1004  compresses the gas inside. As the gas compresses, the gas applies an increasingly greater force to the knob  326 . In such way, the gas within chamber  1004  acts as a passive restoring element applying increased force on the body when the body is in contact with the culture medium. In such case, the chamber  1004  is thoroughly sealed, with seals provided between the knob  326  and a wall of the chamber, such that air or gas neither enters nor escapes from the chamber  1004 . 
     In a variation of such embodiment, the device may further include a conduit  1002  connected to a pump, tank or regulator device for supplying or withdrawing gas from the chamber  1004 . In such case, gas can be actively supplied to the chamber when increased downforce is to be applied to the body. In a particular example, gas can be withdrawn from the chamber through the conduit to apply reduced force to the body or to move the body upwards. 
     Although the above-described embodiments refer to use of a consumable picktool that is received by the device and used to collect a specimen after which the picktool is discarded, the principles and embodiments of the invention can apply also to devices in which the picktool remains an integral part of the device for the repeated collection of specimens, and the picktool is generally not discarded unless damaged or worn. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the scope of the present invention as defined by the appended claims. 
     It will be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims. It will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments.