Abstract:
Apparatus for making a fluid flow connection includes a pair of complementary components having respective first and second flow passages, and respective formations engageable to join the components by press-fitting them together so that the passages are in fluid flow communication and the junction between them is sealed against leakage up to a pre-determined pressure of the fluid flow. The respective formations comprise, on one hand, a spike ( 30 ) including at least a portion ( 32 ) of the first flow passage opening at a tip ( 31 ) of the spike and a first guide surface ( 29 ) about the spike, and, on the other hand, a body ( 41 ) with a pas sageway ( 42 ) that, when the components are press-fitted together, sealingly receives the spike, and a second guide surface ( 47 ) about the passageway that slidingly engages the first guide surface.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the connection of components, fittings and conduits in fluid handling equipment, but is especially useful for making fluid-tight connections in small-scale fluid handling applications, for example in precision analysis systems. The invention more particularly provides apparatus for making a fluid flow connection. 
       BACKGROUND OF THE INVENTION 
       [0002]    In analytical chemistry there are a range of sophisticated techniques available such as chromatography, mass spectrometry and other spectroscopy techniques but rarely can a raw sample be introduced directly into the instrument. Some modification of the sample is usually required, for example removal of interfering matrix, elimination of components that will interfere in the analysis, concentration of the sample, or switching the matrix or solution in which the sample components of interest are dissolved. 
         [0003]    There are a variety of techniques involved in sample preparation but amongst the most common are filtering, targeted pre-separation to simplify the sample, concentration of the sample and changing the matrix. It has been reported that 40% of all analytical sample preparation requires Solid Phase Extraction (SPE) and 60% of all analytical sample preparation requires sample filtering during the procedure. 
         [0004]    Syringes are used in many areas of laboratories including sample preparation for instrumental analysis. Fundamentally a syringe fulfils a dual role as a pump for displacing fluids and as a metering device for accurately determining the precise volume dispensed and the rate it is dispensed. Syringes are used manually by hand or motor driven for automated operation. 
         [0005]    A simple precision connection between a syringe and a fitting is particularly important for applications where a syringe becomes an integral part of a micro analytical or biotech procedure. One such application is direct mass spectrometry injection where typically very low volumes and flow rates are used to aspirate sample from a syringe. 
         [0006]    These methods can often include fittings containing a separation medium (e.g. a micro solid phase extraction (SPE) separation bed) where analyte is preferentially eluted and loaded directly onto the mass spectrometer. 
         [0007]    More generally, evolution of sample preparation, analytical methods and instruments has necessitated the development of a new generation of precision liquid handling devices. Automation has also imposed new requirements on liquid handling, particularly with fittings and elements connected to pipettes, syringes and pumps such as needles, filters and sample preparation tools. Automation of fluid handling systems can require the automated disconnection an reconnection of components in the flowpath. 
         [0008]    The most common ways to securely connect syringes, fittings and tools to another element are luer locks and screwthreads. However, luer lock fittings have a number of short falls when used for precision flow and automated operations. These include the imprecise connecting surfaces requiring mechanical twisting on a thread to be able to generate sufficient force on the sealing faces to make a pressure tight seal. In addition, with a luer lock fitting there is significant dead volume between mating parts. A standard screwthread can be used for a wide range of connections, but also requires a turning motion to engage and disengage fittings. It will thus be appreciated that conventional connection processes typically require a twisting motion that adds complexity if automation is desired. 
         [0009]    It is an object of the invention to provide an improved or at least alternative arrangement for making a fluid flow connection. 
         [0010]    Reference to any prior art or background information in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art or background information forms part of the common general knowledge in Australia or any other jurisdiction; or that this prior art or background information could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. 
       SUMMARY OF THE INVENTION 
       [0011]    The apparatus of the invention entails a co-operative combination of a spike and a surrounding guide surface on the one hand, and a receiver of the spike and a complementary guide surface on the other. 
         [0012]    The invention accordingly provides an apparatus for making a fluid flow connection that includes a pair of complementary components having respective first and second flow passages, and respective formations engageable to join to the components by press-fitting them together so that the passages are in fluid flow communication and the junction between them is sealed against leakage up to a pre-determined pressure of the fluid flow. The respective formations comprise, on one hand, a spike including at least a portion of the first flow passage opening at a tip of the spike and a first guide surface about the spike, and, on the other hand, a body with a passageway that, when said components are press-fitting together, sealingly receives the spike, and a second guide surface about the passageway that slidingly engages the first guide surface. 
         [0013]    There invention also provides a component for a connection apparatus, comprising a body, and a spike including at least a portion of a flow passage opening at the tip of the spike. The body defines a first guide surface about the spike, and the component is configured to be press-fitted with a complementary component having a body with a passageway that sealingly receives the spike and a second guide surface about the passageway that slidingly engages the first guide surface. 
         [0014]    The invention still further provides a component for a connection apparatus, comprising a body with an open-ended passageway and a second guide surface about the passageway. The component is configured to be press-fitted with a complementary component having a spike that includes at least a portion of a fluid passage opening at the tip of the spike and that is sealingly received by said passageway, and further having a body that defines a first guide surface about the spike that slidingly engages the second guide surface. 
         [0015]    Preferably, the first guide surface is an inner surface of a tube surrounding the spike, and the second guide surface is a cylindrical surface surrounding the passageway. 
         [0016]    In one or more embodiments the spike, the passageway and the first and second guide surfaces are of respective uniform cross-section and are mutually co-axially arranged. 
         [0017]    Advantageously, the passageway sealingly receives the spike in an interference fit. 
         [0018]    The respective components are preferably integral components. 
         [0019]    In an application of particular interest, at least one of the first and second passages, preferably the second, includes a medium selected to treat or modify fluid e.g. sample-containing fluid, flowing therethrough. The medium may be a sorbent bed selected to trap targeted compounds from the fluid as it passes through the sorbent bed, for subsequent recovery from the bed by an elution solvent. The at least one passage may be one of two flow paths that are configured in parallel. The other flow path may contain a one-way check valve. 
         [0020]    As used herein, except where the context requires otherwise, the term “comprise” and variations of the term, such as “comprising”, “comprises” and “comprised”, are not intended to exclude further additives, components, integers or steps. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: 
           [0022]      FIG. 1  is an axial cross-sectional view of the separated components of connection apparatus according to an embodiment of the invention, axially aligned but not joined; 
           [0023]      FIG. 2  is a fragmentary three-dimensional view of the two components; 
           [0024]      FIG. 3  is a view corresponding to  FIG. 1  but showing the components fully coupled together to form a connection that is fluid type up to a, predetermined pressure of the fluid flowing therethrough; 
           [0025]      FIG. 4  is a view corresponding to  FIG. 3  but depicting the apparatus connecting a syringe to a column or other flow line via a medium selected to treat or modify fluid flowing therethrough; 
           [0026]      FIG. 5  illustrates a modification of the arrangement shown in  FIG. 4 ; 
           [0027]      FIGS. 6 and 7  depict further alternative configurations for providing a separation bed respectively without and with a parallel valve; 
           [0028]      FIG. 8  is a diagram illustrating a sequence of operations in a robotic automation workflow employing apparatus according to  FIGS. 1 to 3 ; and 
           [0029]      FIGS. 9 to 11  are diagrams of alternative robotic sequences. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0030]    The connection apparatus  10  illustrated in  FIGS. 1 to 3  includes a male component  20  and a female component  40 . The male component  20  is, for this embodiment, especially adapted as an end-fitting for a positive displacement syringe and is illustrated in this context in  FIGS. 4 and 5 . The component  20  comprises a pair of axially symmetrical integrally moulded parts, i.e. a housing  22  and a rear central tube  24 . Housing  22  includes a central annulus  23  that integrally joins a rearwardly trailing cylindrical skirt  25  of larger diameter and a forwardly projecting drive tube  26  of lesser diameter. The housing is strengthened by a transverse web  27  located at the forward side of annulus  23 . 
         [0031]    Annulus  23  and web  27  thereby define a central seat  24 a for an enlarged head at one end of tube  24 , which extends rearwardly, co-axially with skirt  25 , to a slightly further extent than the skirt, and has a spacer rib  28  that abuts annulus  23 . Housing  22  and tube  24  are secured together by a suitable adhesive. 
         [0032]    The central bore  24 b of tube  24  mounts a hollow spike  30  that is sealingly secured in the bore and extends from an inner end at the rear of tube  24  to an outer tip  31  just behind the forward edge of guide tube  26 , passing through an aligned hole  27 a, in web  27 . The interior of spike  30  defines a first flow passage  32  that opens at the tip  31  of the spike, and the interior cylindrical surface of guide tube  26  defines a first guide surface  29  about the, spike. 
         [0033]    In a practical implementation, male component  20  is fitted, as shown in  FIG. 4 , as an end-fitting of a positive displacement syringe  60  having a barrel  62  and a plunger  64  slidably received in the barrel. The plunger  64  has a plunger tip  65  at its inner end and an engagement head  66  at its, outer end that may be gripped by hand or by any suitable mechanism for driving the plunger. 
         [0034]    Female component  40  also has an integral moulded housing  41  that defines an annulus  43  integrally joining a cylindrical trailing skirt  45  of larger diameter and a forwardly projecting alignment guide tube  46  of smaller diameter. The outer cylindrical surface of alignment guide tube  46  defines a second guide surface  47  that is dimensioned to slidably engage the first guide surface  29  on guide tube  26  of the male component. 
         [0035]    The hollow interior of alignment guide tube  46  provides a passageway  42  that, when the male and female components  20 ,  40  are press fitted together in an, axial direction, sealingly receives&#39; spike  30 , as illustrated in  FIGS. 3 and 4 . To facilitate engagement of the components, passageway  42  has a tapered entry  44  to receive spike  30 , while first guide surface  29  includes tapered entry  36  to receive second guide surface  47 . 
         [0036]    Suitable materials for the male and female components  20 ,  40  include polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE) (Teflon), nylon, polypropylene and polyethylene. It is found that the female component  40  is preferably formed in a softer material than the male component  20  in order to achieve optimum sealing properties. 
         [0037]    By accurately dimensioning the diameter and uniformity of passageway  42  relative to the spike so that the passageway receives the spike in a substantially precise interference fit, it is possible to achieve a high sealing pressure rating for the combination and a low dead volume. It will be appreciated that the arrangement of the illustrated embodiment exposes only a very small surface area to the fluid flow path. Fluid pressure can be very high but is only applied to the annular area of the spike, which for example in the case of a 0.5 mm diameter spike is 0.20 mm 2 . At a pressure of 70 kg/cm 2  (1,000 psi), the applied load pushing the connection apart is only 0.14 kg. It is found that this is insufficient force to overcome the friction from the interference fit between the hollow spike  32  and the diameter of passageway  42 . The cross-sectional area of the fluid path can potentially hold pressures greater than 1,000 psi, and even up to and greater than 1,500 psi. 
         [0038]    It will be appreciated that a good and accurate match between the diameters of guide surfaces  29 ,  47  is valuable in the seamless engagement of the components. 
         [0039]    The inventive concept can be incorporated into a broad range of applications and fittings. Termination of elements such as syringes, pumps, needles, analytical columns, filter cartridges, SPE cartridges, sample preparation cartridges, manifolds, injector connections, detector connections, direct mass spectrometer interfaces, automated pick up and drop off, robotic fluid connections and so on can readily incorporate a connection apparatus according to the invention. 
         [0040]      FIG. 4  illustrates the application of the invention where the male component is mounted as an end-fitting for a syringe, as already described, and the female component serves as a micro solid phase extraction (SPE) cartridge. A rear ferrule  48  adhesively secured within housing skirt  45  sealingly mounts an appropriate length of hollow column or tubing  49 . The solid phase medium  55  occupies the volume between ferrule  48  and housing annulus  43  and is thus provided in the flow passage defined within the female component  40 . The arrangement illustrated in  FIG. 4  has proven effective for high pressure connections of a positive displacement syringe with a 5 micron ODS microSPE cartridge. Accurate volumes of sample and solvent have been delivered without leakage or loss. Minimal dead volume effects were observed when using the illustrated configuration. 
         [0041]    It will be understood that the illustrated arrangement has the significant advantage of a press fit and therefore no requirement for a rotary or twisting motion. It thus permits simple automated engagement and disengagement. The arrangement provides an ultra-low dead volume connection to enable full sample of delivery to and from the syringe with minimum cross-contamination. The connection is also suited for rapid robotic automation, allowing simple pick up and drop off without twisting or turning. There is minimal risk of failure on pick up or sealing of the connection. 
         [0042]      FIG. 5  illustrates the application of the present invention in combination with a concept disclosed in international patent application PCT/AU2012/001291. The female component  40  has two flow paths  56 ,  57  that are configured in parallel and respectively contain a one-way check valve  59  and a medium  58  selected to treat or modify fluid flowing therethrough. The one-way check valve is depicted as a ball valve but may alternatively be, for example, a plug seal valve. In advantageous applications the medium  58  is a sorbent separation bed selected to trap targeted compounds from the fluid as it passes through the sorbent bed, for subsequent recovery from the bed by an [insert] solvent. In particular applications, the solvent separation bed may be a solid stationary phase bed for practising solid phase extraction (SPE) or micro extraction by packed solvent (MEPS) of the targeted compounds. The medium may be selected from the group comprising filtering media, monoliths and immobilised biologically active materials. 
         [0043]    In the arrangement depicted in  FIG. 5 , the medium is a short separation bed  58  for micro SPE with a parallel valve  59 . In  FIG. 6  there is no valve but an extended separation bed  158 , while in  FIG. 7  there is a ‘column’ length separation bed  258  with a parallel one-way check valve  259 . In  FIGS. 6 and 7 , like parts are indicated by like reference numerals preceded by a “1” and “2” respectively. 
         [0044]    A particular operational advantage of the illustrated embodiments with a one-way check valve is that when the syringe plunger is retracted to aspirate fluid into the syringe, the reduced pressure in the syringe opens the valve and there is then sufficient restriction to flow through the medium bed to substantially prevent any flows through the bed when the valve is opened. On the other hand, once the fluid has been drawn into the syringe and the plunger is depressed, the check valve defaults to its closed position, assisted by the pressure generated in the syringe barrel by the back pressure due to restriction of flow through the media bed. With the valve closed, the dispensed fluid will flow only through the bed to exit through the needle of the syringe. 
         [0045]    More extensive discussion of the embodiments of  FIGS. 5 and 7  will be found in the aforementioned international patent application PCT/AU2012/001291, the entire contents of which is incorporated herein by a reference. 
         [0046]    The inventive concept is ideal for robotic automation applications. Engagement and disengagement of the male and female components, without twisting or turning of parts, eliminates the need for complex automation apparatus, processes and programming. Simple push/pull fittings allow multiple fittings to be sequenced during a workflow operation with fittings being easily picked up and then dropped off using a simple fork device. 
         [0047]    A typical automated sequence is illustrated in  FIG. 8 . The syringe  60  (fitted with the male component  20  illustrated in  FIG. 1 ) picks up a micro SPE cartridge or filter  63  incorporating the female component  40  from a holder  70  with a push operation  71 . The micro SPE is then used for processing the sample from a sample tube or other receptacle  72 . When completed, a fixed fork  74  is used to expel the micro SPE cartridge  63  from the syringe using a pull operation  75 . These sequences can be simply programmed into the workflow of most automated robotic systems. The process can be extended to using multiple fittings throughout a sample preparation workflow. 
         [0048]    Further exemplary robotic sequences are illustrated in  FIGS. 9 to 11 .