APPARATUS FOR SAMPLING A FLUID

Abstract: Apparatus for sampling blood by puncturing a skin through which the blood can be obtained, includes a housing (2) providing a surface against which a human thumb (22) can be placed. An aperture (6) in said surface communicates with a chamber defined by the housing (2). A needle (20) is supported in said chamber. The base of the housing (2) is dome-shaped for imparting to the needle (20) when pressed beyond its point of inversion an acceleration in the direction of the aperture (6) to propel said needle (20) though the aperture (6) to puncture the skin, and subsequently to withdraw the needle (20) from the skin to enable blood to pass through the punctured skin into the chamber.

Description: -1 - - APPARATUS FOR SAMPLING A FLUID The present invention relates to apparatus for sampling a fluid, for example, for sampling and testing blood for a predetermined condition. Kits for sampling and testing blood for diagnosing diabetes are known. Such kits employ a gadget for firing a needle to pierce the skin of the patient and a separate container holding a cocktail mixture into which blood from the patients pierced skin can be dripped. The colour of the cocktail mixture when blood is added will indicate the likelihood of the patient having a diabetic condition. The disadvantage of this arrangement is that the kit is cumbersome to operate and the procedures to be adopted are not always clearly '• •understood by the patient who normally has to operate : the kit himself based on the written instructions accompanying the kit. Furthermore, the gadget for piercing the skin is somewhat of a fearsome device in that it involves a trigger for releasing a spring loaded needle which upon release is directed at high speed into the skin in full view of the patient. This is often off-putting to the user. According to the present invention there is provided apparatus for sampling a fluid by puncturing a skin through which said fluid can be obtained, the apparatus comprising a housing having a roof providing a surface for contacting said skin, an aperture in said roof communicating with a chamber defined by the housing, a needle supported in said chamber and means for imparting to said needle an acceleration in the direction of said aperture to propel said needle through the aperture to puncture the skin, and subsequently to withdraw the needle from the skin to enable said fluid to pass through the punctured skin into the chamber. According to the present invention there is further provided apparatus for puncturing a skin comprising a housing having a roof defining a surface arranged to engage an area of skin to be punctured, an opening in said roof, a needle mounted in said housing for movement towards and through said opening and propulsion means operable when actuated to apply a propelling force to the needle to drive the needle partially through the opening to puncture any skin placed on- said surface. Blood sampling and testing apparatus embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figures 1 to 4 are sections through a first embodiment of the invention at four different stages during the operation of the apparatus; and Figures 5 to 8 are sections through a second embodiment of the invention at four different stages during the operation of the apparatus. The blood sampling and testing apparatus or unit shown in Figure 1 is arranged to sample the blood of a patient and to test it to ascertain whether or not the patient has a diabetic condition. The apparatus is in the form of a disposable unit so that once a sample of blood has been taken and tested the unit may be discarded. As shown in Figures 1 to 4 the unit comprises an inverted cylindrical transparent container 2 with an open base and'a concave opaque roof 4- The roof 4 has a central aperture 6 and an array of radially directed, equiangularly spaced grooves 8 in the outer surface thereof, each groove 8 communicating with the central aperture 6. Advantageously the grooves 8 may be three in number. The roof 4 supports a downwardly depending cylindrical guide member 10 having an axial length equal to just over one half of the axial length of the container 2. The lower extremity of the container 2 is of reduced external diameter to receive a cap member 12. The cap member 12 has a rim 14 which is arranged to engage the lower extremity of the container 2 and is provided with a plurality of concentric annular steps 16 which terminate in a central thimble-shaped protrusion 18. When the cap member 12 is mounted on the container 4, the protrusion 18 extends into the cylindrical guide 10 which guide acts to constrain the ' protrusion 18 for movement along its longitudinal axis. The head of the protrusion 18 supports the end portion of a hyperdermic needle 20 which is mounted so as to be in alignment with the central aperture 6 in the roof 4 of the container 2. The needle 20 can be embedded in the protrusion. The container 4 is of rigid plastics while the cap 12 is of flexible plastics. . When assembled, the cap member 12 is adhesively secured or heat-sealed to the container 4 and the container 4 is at least partially filled with an enzyme cocktail suitable for .detecting a diabetic condition. A flexible disk 22 coated with a pressure sensitive adhesive is placed on the roof 4 to seal the grooves 8 and the aperture 6 against the egress of liquid from the container 4- The disk 22 is advantageously provided with a tab (not shown) to enable the disk to be readily stripped off the roof 4 when needed for use. . In operation a patient grasps the tab of the disk and strips it from the roof 4 to provide open access to the cocktail within the container 2 through the aperture 6. The patient then places his thumb 24 or some other part of his anatomy from which blood is to be drawn, on to the concave roof 4« Then using a free finger the patient applies pressure to the cap member 12 to push the thimble-shaped protrusion 18 inwardly. The stepped portion 16 of the cap initially offers increasing resistance to the applied pressure until it is deformed to an extent where it starts to undergo an inversion. At this point, resistance to pressure decreases rapidly with the consequent effect that the protrusion 18 is accelerated towards the r-oof 4. The needle 20 which is rigid ' with the protrusion 18 undergoes the same acceleration to which the protrusion 18 is subjected and is projected through the aperture 6 into the skin of the patient (see Figure 2). The movement of the needle 20 is halted when the protrusion 18 strikes the underside of the roof 4. As the thimble-shaped protrusion is displaced inwardly the volume of the container is reduced and the free air and also possibly some liquid will tend to be expelled through the aperture 6. Because the thumb is blocking the aperture the grooves 8 provide an escape route for this excess air and liquid. When the pressure on the cap member 12 is released the cap member 12 will recover under its natural resilience and accordingly the protrusion 18 will withdraw the needle 20 from the skin. As the cap member t2 returns to its original configuration (see Figure 3) blood will drip from the pierced skin through the aperture 6 into the cocktail within the container. When a sufficient quantity of blood has been released into the container 2 the pressure adhesive disk 22 is replaced (see Figure 4) and the unit shaken to ensure good mixing. The colour of the cocktail will then indicate the result of the test. Once the result of the test has been noted the now sealed unit is discarded. A new unit is required for a fresh test. It will be appreciated that the pressure of the thumb on the roof 4 will cause that part of the thumb exposed by the aperture 6 to bulge to provide a "pinch effect". This effect is particularly advantageous since when skin is pinched prior to the insertion ' of a needle the pain threshold of the patient in the pinched area is increased. In order to achieve a good "pinch effect" the ratio of the area of the roof to the area of the opening is preferably less than 10:1 but not greater than 20: 1. In the apparatus or unit shown in Figures 5 to 8 parts similar to those in Figures 1 to 4 are similarly referenced. As shown, the container 2 has adjacent its lower end an inwardly directed annular flange 30. On the underside of the roof 4 instead of the cylindrical guide of Figure 1 an annular abutment member or stop 32 is provided. A spiral helical spring 28 compressed into a planar configuration is shown in Figure 5 - The radially outer turn of the spring 28 is secured (for example by an adhesive) to the underside of the flange 30. The radially inner turn of the spring 28 supports a platform 34 carrying a needle 20. The underside of the platform 34 supports a retaining ring 36 defining a circumferentially extending retaining groove 38. The cap member 12 instead of defining a thimble-shaped protrusion as with the cap member of Figure 1 defines a small inwardly directed centering dimple 40. On the inner face of the cap member 12 in spaced apart relationship are a pair of upstanding gripping fingers 42. The tip of each gripping finger has a projection 42a which is arranged to engage the groove 38 in the annular member and so hold the platform 34 in position against the bias of the spring 28. The spring when in its relaxed state adopts the configuration shown in Figure 7. In operation the procedure. adopted in obtaining a blood sample is generally as hereinbefore described with reference to Figures 1 to 4- When, however, pressure is applied to the cap member 12 the curvature developed by the cap member will cause the two fingers 42 to become inclined away from one another so that their tips 42a. become disengaged from the groove 38 in the annular flange 36. The spring force of the spring 28 is now released whereupon the platform 34 and needle 20- are propelled towards the aperture 6. The displacement of the platform 34 is halted when it abuts the stop 32 (see Figure 6) and this limits the penetration of the needle into the skin. Because the spring has been released so suddenly it will overshoot its mean position so consequently once the skin has been pierced the needle will be retracted by the spring and eventually settle in the position indicated in Figure 7. Once sufficient blood has been drawn, the unit is resealed with the disk 22 (as indicated in Figure 8) and after the test results have been noted is discarded. While the arrangement described is suitable for drawing blood from a patient it will be appreciated that the arrangement can be readily adapted to introduce liquids into the blood of a patient for purposes of innocculation for example. The needle is preferably arranged to be hollow and modifications would need to be made to ensure that no air from the container enters the patient. It will also be appreciated that different patients have different thicknesses and toughnesses of skin, accordingly needles of different length may be used and the force applied to the needle varied. Units 'with different properties in this respect may be colour coded with different colours for easy identification. It will also be appreciated that the units described are not limited for use in testing for a diabetic condition but can be used to test for other conditions or merely for obtaining a blood sample supported in a preserving environment for use in subsequent tests. It will further be appreciated that said cap member 12 may be of dome-shaped configuration instead of the stepped configuration shown in the drawings. It will be appreciated that the needle and the spring can both be of plastics material or a composite of plastics and other material. Also while it is important that the roof should be opaque to hide the needle from the patient's view the housing may also be opaque but be provided with a small viewing window to enable the fluid in the container to be inspected without exposing the needle to the viewer.

Claims: CLAIMS 1. Apparatus for puncturing a skin comprising a housing having a roof defining a surface arranged to engage an area of skin to be punctured, an opening 5 in said roof, a needle mounted in said housing for movement towards and through said opening and propulsion means operable when actuated to apply a propelling force to the needle to drive the needle partially through the opening to puncture any skin 0 placed on said surface. 2. Apparatus according to claim 1 , wherein said propulsion means is arranged also to retract the needle back through the opening following its initial displacement therethrough. 5 3- Apparatus according to claim 1 or to claim 2, wherein said propulsion means are formed by a • - flexible wall of the housing. 4- Apparatus according to claim 3, wherein said flexible wall is generally dome-shaped.. 0 ~ . Apparatus according to claim 3, wherein said flexible wall is of generally stepped dome- shape. 6. Apparatus according to claim T or to claim 2, wherein said propulsion means comprises a coiled 5 spring. 7. Apparatus for sampling a fluid by puncturing a skin through which said fluid can be obtained, the apparatus comprising a housing having a roof providing a surface for contacting said skin, an 0 aperture in said surface communicating with a chamber defined by the housing, a needle supported in said chamber and means for imparting to said needle an acceleration in the direction of said aperture to propel said needle through the aperture to puncture 5 the skin, and subsequently to withdraw the needle from the skin to enable said fluid to pass through the punctured skin. 8. Apparatus according to claim 7, wherein the chamber contains a testing substance to effect a test on the fluid when it is caused to enter the chamber. ~ . Apparatus according to claim 7 or to claim 8, wherein the acceleration imparting means comprises a flexible cap member of predetermined configuration carrying said needle, said predetermined configuration being such that when pr-essure is applied to said cap member in a direction to displace said needle towards the aperture, the resistance of said cap member to displacement will increase progressively to a point at which inversion occurs and thereafter the resistance to pressure progressively decreases. 10. Apparatus according to claim 9 - wherein the flexible cap member is of concentric stepped configuration. 11. Apparatus according to claim 7 or to claim 8, wherein the acceleration imparting means comprises a compressed spring carrying said needle, and trigger means for releasing the force of the spring. 12. Apparatus according to claim 11, wherein the trigger means comprises a pair of spaced fingers mounted on said cap in spaced apart relationship, said fingers being arranged to hold said spring in its compressed state, the displacement of the cap being arranged to effect change in the curvature of the cap such that said fingers are moved apart to release said spring. 13- Apparatus according to any preceding claim, wherein said surface is provided with grooves to ' provide a passage between said surface and said skin to and from the aperture or opening. "14. Apparatus according to any preceding claim wherein the said surface is concave. 15- Apparatus according to any preceding claim, said apparatus being substantially the same order of size as a human thumb.

Inventors: PALMER GEOFFREY CHARLES, RENFREW BRUCE JAMES, PALMER, GEOFFREY, CHARLES, RENFREW, BRUCE, JAMES
Applicants: PALMER GEOFFREY CHARLES, RENFREW BRUCE JAMES, PALMER, GEOFFREY, CHARLES, RENFREW, BRUCE, JAMES
Application year: 1985
Main classification: A61B5
IPC codes: A61B5, A61B17