Method of preventing short sampling of a capillary or wicking fill device

• US 6,823,750 B2
• Filed: 04/04/2003
• Issued: 11/30/2004
• Est. Priority Date: 03/27/2000
• Status: Expired due to Fees

• Current Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Hodges, Alastair McIndoe
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US10/408,836
• Publication Number:
  US 20040040394A1
• Time in Patent Office: 606 Days
• Field of Search: 738/648--86, 738/640--86, 738/647.2, 738/63, 738/649.1, 73/645.6, 738/648.1, 738/645.1, 422/55-58, 422/68.1, 422/101-102, 422/50, 422/69, 204/403, 204/556, 436/180, 435/14, 600/584
• US Class Current: 73/864.72
• CPC Class Codes: A61B 2562/0295 Strip shaped analyte sensors for apparatus classified in A61B5/145 or A61B5/157 disposable multilayered or laminated electrodes G01N27/307; details of handling chemical test elements G01N33/4875
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/069 Absorbents; Gels to retain a fluid
• CPC Class Codes: B01L 2300/0825 Test strips
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2300/165 Specific details about hydrophobic, oleophobic surfaces
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 3/5023 with a sample being transported to, and subsequently stored in an absorbent for analysis
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: B01L 3/50273 characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• CPC Class Codes: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: B01L 3/502746 characterised by the means for controlling flow resistance, e.g. flow controllers, baffles B01L3/502738 takes precedence
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

The current invention provides a device, and a method for using the device, for ensuring that a capillary or wicking fill device is fully filled. In particular this invention is directed to, but not limited to, use with capillary or wicking action filled electrochemical sensors suitable for use in analyzing blood or interstitial fluids.

Claims

1. A device for sampling a fluid, comprising a pre-chamber having an interior surface and a first volume, the pre-chamber being capable of exerting a first capillary force, the device further comprising a sensing chamber in fluid communication with the pre-chamber, the sensing chamber having an interior surface and a second volume, the sensing chamber being capable of exerting a second capillary force, wherein the first volume is not less than the second volume, and wherein a differential exists between the capillary forces, the differential being sufficient to cause flow of fluid from the pre-chamber to substantially fill the sensing chamber.

2. The device of claim 1, wherein the interior surface of the pre-chamber comprises at least first and second pre-chamber walls spaced apart at a first distance to define a pre-chamber height, and wherein the interior surface of the sensing chamber comprises at least first and second sensing chamber walls spaced apart at a second distance to define a sensing chamber height, wherein the height of the sensing chamber is less than the height of the pre-chamber, and wherein the differential capillary force derives at least in part from a difference between the pre-chamber height and the sensing chamber height.

3. The device of claim 1, the interior surface of the pre-chamber having a first surface roughness, a first actual surface area, and a first geometric surface area, and the interior surface of the sensing chamber having a second surface roughness, a second actual surface area, and a second geometric surface area, wherein the second surface roughness is greater than the first surface roughness, and wherein the differential capillary force derives from a difference between the second surface roughness and the first surface roughness, and wherein the surface roughness is defined as the actual surface area divided by the geometric surface-area.

4. The device of claim 1, the interior surface of at least the pre-chamber or the sensing chamber comprising a surface treatment, wherein the differential capillary force derives from the surface treatment.

5. The device of claim 4, wherein the surface treatment comprises a hydrophilic substance.

6. The device of claim 4, wherein the surface treatment comprises a hydrophobic substance.

7. The device of claim 4, wherein the surface treatment comprises a substance selected from the group consisting of a surfactant, a block copolymer, a hygroscopic compound, an ionizable substance, and mixtures thereof.

8. The device of claim 4, wherein the interior surface of the pre-chamber comprises a first surface treatment and the interior surface of the sensing the chamber comprises a second surface treatment.

9. The device of claim 1, further comprising a porous material, wherein the porous material contributes to the capillary force of at least one of the pre-chamber and the sensing chamber.

10. The device of claim 9, wherein both the pre-chamber and the sensing chamber comprise a porous material.

11. The device of claim 9, wherein the porous material is selected from the group consisting of a sintered powder and a macroporous membrane.

12. The device of claim 9, wherein the porous material comprises a macroporous membrane comprising a polymeric material, wherein the polymeric material is selected from the group consisting of polysulfone, polyvinylidenedifluoride, nylon, cellulose acetate, polymethacrylate, polyacrylate, and mixtures thereof.

13. The device of claim 1, further comprising a powder, wherein the powder contributes to the capillary force of at least one of the pre-chamber and the sensing chamber.

14. The device of claim 13, wherein both the pre-chamber and the sensing chamber comprise a powder.

15. The device of claim 13, wherein the powder is insoluble in the sample.

16. The device of claim 13, wherein the powder is soluble in the sample.

17. The device of claim 13, wherein the powder comprises a material selected from the group consisting of microcrystalline cellulose, soluble salts, insoluble salts, and sucrose.

18. The device of claim 1, wherein the pre-chamber and the sensing chamber comprise two or more materials, which can be the same or different, selected from the group consisting of a mesh material, a fibrous filling material, a porous material, and a powder.

19. The device of claim 1, wherein the sensing chamber comprises electrodes capable of use in an electrochemical cell.

20. The device of claim 19, wherein the electrodes are spaced apart by 600 microns or less.

21. The device of claim 19, wherein the electrodes are spaced apart by 400 microns or less.

22. The device of claim 19, wherein the electrodes are spaced apart by 200 microns or less.

23. The device of claim 1, further comprising a detector capable of detecting a condition wherein the pre-chamber contains a volume of fluid sufficient to substantially fill the sensing chamber.

24. A glucose monitoring test strip comprising the device of claim 1.

25. A device for sampling a fluid, comprising a pre-chamber having an interior surface and a first volume, the pre-chamber being capable of exerting a first capillary force, the device further comprising a sensing chamber in fluid communication with the pre-chamber, the sensing chamber having an interior surface and a second volume, the sensing chamber being capable of exerting a second capillary force, wherein the first volume is not less than the second volume, and wherein a differential exists between the capillary forces, the differential being sufficient to cause flow of fluid from the pre-chamber to substantially fill the sensing chamber, and wherein the device further comprises a mesh material and the mesh material contributes to the capillary force of at least one of the pre-chamber and the sensing chamber.

26. The device of claim 25, wherein both the pre-chamber and the sensing chamber comprise a mesh material.

27. A device for sampling a fluid, comprising a pre-chamber having an interior surface and a first volume, the pre-chamber being capable of exerting a first capillary force, the device further comprising a sensing chamber in fluid communication with the pre-chamber, the sensing chamber having an interior surface and a second volume, the sensing chamber being capable of exerting a second capillary force, wherein the first volume is not less than the second volume, and wherein a differential exists between the capillary forces, the differential being sufficient to cause flow of fluid from the pre-chamber to substantially fill the sensing chamber, and wherein the device further comprises a fibrous filling material that contributes to the capillary force of at least one of the pre-chamber and the sensing chamber.

28. The device of claim 27, wherein both the pre-chamber and the sensing chamber comprise a fibrous filling material.

29. The device of claim 27, wherein the fibrous filling material comprises a material selected from the group consisting of polyolefin, polyester, nylon, cellulose, polystyrene, polycarbonate, and polysulfone.

30. The device of claim 27, wherein the fibrous filling material comprises a nonwoven or melt blown polymer.