Method and Apparatus for Sampling and Analysis of Fluids

• US 20070232956A1
• Filed: 09/13/2005
• Published: 10/04/2007
• Est. Priority Date: 09/13/2004
• Status: Active Grant

• Current Assignee: Microsample Ltd.
• Original Assignee: Microsample Ltd.
• Inventors: Harman, Anthony, Cassells, John
• Granted Patent: US 8,092,394 B2
• Time in Patent Office: Days
• US Class Current: 600/573
• CPC Class Codes: A61B 17/205 Vaccinating by means of needles or other puncturing devices
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150167 Adjustable piercing speed of skin piercing element, e.g. blade, needle, lancet or canula, for example with varying spring force or pneumatic drive
• CPC Class Codes: A61B 5/150183 Depth adjustment mechanism using end caps mounted at the distal end of the sampling device, i.e. the end-caps are adjustably positioned relative to the piercing device housing for example by rotating or screwing
• CPC Class Codes: A61B 5/15019 Depth adjustment mechanism using movable stops located inside the piercing device housing and limiting the travel of the drive mechanism mechanisms using distal end caps A61B5/150183, mechanisms at the piercing element carrier proximal end A61B5/150198
• CPC Class Codes: A61B 5/150213 Venting means
• CPC Class Codes: A61B 5/150236 Pistons, i.e. cylindrical bodies that sit inside the syringe barrel, typically with an air tight seal, and slide in the barrel to create a vacuum or to expel blood
• CPC Class Codes: A61B 5/150244 Rods for actuating or driving the piston, i.e. the cylindrical body that sits inside the syringe barrel, typically with an air tight seal, and slides in the barrel to create a vacuum or to expel blood
• CPC Class Codes: A61B 5/150358 Strips for collecting blood, e.g. absorbent optical reagent test strips G01N21/8483; chemical reagent test strips G01N33/4875, G01N33/52
• CPC Class Codes: A61B 5/150435 Specific design of proximal end
• CPC Class Codes: A61B 5/150503 Single-ended needles hollow piercing element tip design A61B5/150396, needle sets for catheters A61M25/06, needles for bringing media into the body A61M5/32
• CPC Class Codes: A61B 5/150587 by friction fit
• CPC Class Codes: A61B 5/150717 manually removed
• CPC Class Codes: A61B 5/150755 Blood sample preparation for further analysis, e.g. by separating blood components or by mixing
• CPC Class Codes: A61B 5/150946 Means for varying, regulating, indicating or limiting the speed or time of blood collection
• CPC Class Codes: A61B 5/15105 Purely manual piercing, i.e. the user pierces the skin without the assistance of any driving means or driving devices
• CPC Class Codes: A61B 5/15113 Manually triggered, i.e. the triggering requires a deliberate action by the user such as pressing a drive button
• CPC Class Codes: A61B 5/1519 comprising driving means, e.g. a spring, for propelling the piercing unit
• CPC Class Codes: A61B 5/15194 fully automatically retracted, i.e. the retraction does not require a deliberate action by the user, e.g. by terminating the contact with the patient's skin
• CPC Class Codes: A61B 5/411 : Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 5/441 : Skin evaluation, e.g. for skin disorder diagnosis

Abstract

A medical device having a housing (2) with a bore (3) and a lancet (1) slidably fitting in the bore. The lancet operates as a positive displacement piston. In a retracted position, in which the lancet is rearwardly displaced along the bore to define a fluid-containing space in the bore forwardly on the lancet tip, the fluid-containing space has a cross-section dimension to allow fluid to be retained therein by surface tension. The device has a seal (6) operable substantially to prevent flow of fluid from the fluid-containing space past the seal means on movement of the lancet. Displacement of the lancet between the puncture and retracted positions provides suction for drawing fluid into and along the fluid-containing space from the forward end of the bore, and/or pressure for expelling fluid from the fluid-containing space via the forward end of the bore. Also disclosed are methods for operating the device.

Claims

1. A medical device having a housing with a bore and a lancet slidably fitting in the bore, the lancet being moveable between a puncture position, in which a sharpened tip of the lancet is exposed from a forward end of the bore for a puncture operation, and a retracted position, in which the lancet is rearwardly displaced along the bore to define a fluid-containing space in the bore forwardly of the lancet tip, the fluid-containing space having a cross-section diameter of 5 mm or less to allow fluid to be retained therein by surface tension, the device having seal means operable substantially to prevent flow of fluid from the fluid-containing space past the seal means on movement of the lancet, the seal means being in sliding engagement with a sealing surface, one of the seal means and the sealing surface being fixedly movable with the lancet at least during forward displacement of the lancet, so that displacement of the lancet between the puncture and retracted positions provides at least one of:

(i) suction for drawing fluid into and along the fluid-containing space from the forward end of the bore, and

(ii) pressure for expelling fluid from the fluid-containing space via the forward end of the bore.

wherein the fluid comprises one of a liquid, a mixture of liquids and a mixture of liquid and solid.

2. A device according to claim 1 wherein one of the seal means and the sealing surface is fixedly movable with the lancet during rearward displacement of the lancet.

3. A device according to claim 1 wherein the seal means is formed by the outer surface of the lancet, the sealing surface being an internal surface of the bore.

4. A device according to claim 3 wherein the outer surface of the lancet is profiled to provide the seal means as a surrounding projection.

5. A device according to claim 1 wherein the seal means is a sealing member disposed around the lancet, the sealing surface being an internal surface of the bore.

6. A device according to claim 1 wherein the seal means is a sealing member disposed at the internal surface of the bore, the sealing surface being an outer surface of the lancet.

8. A device according to claim 1 having cooperating means for providing an intermediate delay position for the lancet between the puncture position and the retracted position.

9. A device according to claim 1 having at least one stop member for limiting the forward and/or rearward travel of the lancet.

10. A device according to claim 1 wherein, at the puncture position, the seal means is out of contact with the sealing surface, or contacts the sealing surface with reduced pressure compared with the retracted position, thereby providing low friction for movement of the lancet at the puncture position.

11. A device according to claim 10, as dependent from claim 8 wherein, during retraction from the puncture position, the contacting or increased contacting of the seal means with the sealing surface provides the intermediate delay position.

12. A device according to claim 10 wherein the bore includes a region of increased cross-section dimension for location of the seal means or the sealing surface at the puncture position of the lancet.

13. A device according to claim 10 wherein the seal means or sealing surface is disposed beyond the forward end of the bore at the puncture position of the lancet.

14. A device according to claim 1 wherein the seal means is a sealing member disposed rearwardly in the device from the forward tip of the lancet and movable with the lancet tip and the sealing surface is formed by the internal surface of a sealing region of the bore.

15. A device according to claim 14 wherein a cross-sectional dimension of the sealing member is greater than a cross-sectional dimension of the fluid-containing space but less than or equal to 10 times the cross-sectional dimension of the fluid-containing space.

16. A device according to claim 1 wherein the lancet tip is sharpened to have a radius of curvature in at least one dimension of one quarter or less of the narrowest cross-sectional dimension of a non-tip region of the lancet.

17. A device according to claim 1 wherein the bore includes a chamber portion, disposed between and having a greater cross-sectional dimension than forward and rearward portions of the bore.

18. A device according to claim 17 wherein the cross-sectional dimension of the bore increases stepwise between the forward portion of the bore and the chamber portion.

19. A device according to claim 1 wherein, in use, the fluid-containing space presents means for measuring or testing a characteristic of the fluid to fluid contained in the fluid-containing space.

20. A device according to claim 1 having a secondary conduit from the bore, communicating with the fluid-containing space.

21. A device according to claim 1 having a closure member located forwardly of the lancet tip, sealing at least a part of the fluid-containing space.

22. A device according to claim 21 wherein the closure member is adapted to be removed or punctured by the lancet during operation of the device.

23. A device according to claim 1 wherein said at least part of the fluid-containing space contains a liquid for application to a subject by operation of the device.

24. A device according to claim 1 including a spacer member located forwardly of the forward end of the bore, the spacer member being for contact with the skin of a subject.

25. A device according to claim 24 wherein the spacer member is dimensioned to provide an accumulation space between a puncture in the skin of the subject and the forward end of the bore, fluid from the puncture being able to accumulate in the accumulation space before being drawn into the fluid-containing space by operation of the device.

26. A device according to claim 24 wherein the spacer member includes one or more projections projecting inwardly towards the puncture position of the lancet tip, said projections providing a surface to enhance the flow of an accumulating fluid towards the forward end of the bore.

27. A device according to claim 1 including sensing means for sensing the presence or absence of fluid at the forward end of the bore.

28. A device according to claim 27 wherein the sensing means includes at least two electrodes, at least one of which is located at the forward end of the bore to detect the presence or absence of fluid at the forward end of the bore by measurement of the resistance between the electrodes.

29. A device according to claim 28 wherein the lancet provides one of the electrodes.

30. A device according to claim 1 including sensing means for sensing the presence and/or amount of fluid along the fluid-containing space.

35. A method according to claim 1 including the step, before puncturing the skin of a subject, of expelling fluid from the fluid-containing space onto the skin of the subject at the skin location to be punctured.

7. A device according to wherein the seal means is disposed adjacent the lancet tip, at least when the lancet is in the retracted position.

31. A method of operating a medical device, the device having a housing with a bore and a lancet slidably fitting in the bore, the lancet being moveable between a puncture position, in which a sharpened tip of the lancet is exposed from a forward end of the bore for a puncture operation, and a retracted position, in which the lancet is rearwardly displaced along the bore to define a fluid-containing space in the bore forwardly of the lancet tip, the fluid-containing space having a cross-section dimension to allow fluid to be retained therein by surface tension, the device having seal means operable substantially to prevent flow of fluid from the fluid-containing space past the seal means on movement of the lancet, the seal means being in sliding engagement with a sealing surface, one of the seal means and the sealing surface being fixedly movable with the lancet at least during forward displacement of the lancet, the method including displacing the lancet between the puncture and retracted positions to do least one of:

(i) drawing fluid into and along the fluid-containing space from the forward end of the bore by suction, and

(ii) expelling fluid from the fluid-containing space via the forward end of the bore.

32. A method according to claim 31 wherein the puncture operation of the lancet tip punctures the skin of a subject and the fluid drawn into the fluid-containing space is at least one of the blood of the subject and the interstitial fluid of the subject.

33. A method according to claim 31 including the step, after puncturing the skin of the subject, of delaying retraction of the lancet to allow blood or interstitial fluid to accumulate on the surface of the skin of the subject for subsequent drawing into and along the fluid-containing space.

34. A method according to claim 33 including the step, after puncturing the skin of the subject, partially retracting the lancet to an intermediate delay position, prior to full retraction of the lancet.