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

• US 20070062315A1
• Filed: 10/09/2006
• Published: 03/22/2007
• Est. Priority Date: 03/27/2000
• Status: Abandoned Application

• Current Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Hodges, Alastair
• Application Number:
  US11/544,331
• Publication Number:
  US 20070062315A1
• Time in Patent Office: Days
• US Class Current: 73/864.720
• CPC Class Codes: A61B 2562/0295 Strip shaped analyte sensors for apparatus classified in A61B5/145 or A61B5/157
• 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 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 being capable of exerting a first capillary force, a sensing chamber in fluid communication with the pre-chamber, the sensing chamber having an interior surface and being capable of exerting a second capillary force;

wherein a differential exist between the capillary forces, the differential being sufficient to cause flow of fluid from the pre-chamber to the sensing chamber, and wherein the pre-chamber further comprises a volume such that when full the pre-chamber comprises at least as much sample as is needed to substantially fill the sensing chamber.

4. The device of claim 1, wherein the height of the sensing chamber is defined by an aperture in a space layer.

5. The device of claim 1, wherein the interior surface of the pre-chamber having a first surface roughness, as 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 is defined as the actual surface area divided by the geometric surface area.

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

7. The device of claim 6, wherein the electrodes are spaced apart by a distance of 600 microns or less.

8. The device of claim 6, wherein the electrodes are spaced apart by a distance of 400 microns or less.

9. The device of claim 6, wherein the electrodes are spaced apart by a distance of 200 microns or less.

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

11. The device of claim 10, wherein the surface treatment comprises a hydrophilic substance.

12. The device of claim 10, wherein the surface treatment comprises a hydrophobic substance.

13. The device of claim 10, 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.

14. The device of claim 10, wherein the interior surface of the pre-chamber comprises a first surface treatment and the interior surface of the sensing chamber comprises a second surface treatment.

2. The device of claim 2, 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 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 2, wherein the height of the sensing chamber is defined by layers within the sensing chamber.

15. A method for ensuring that a sensing device is substantially filled with a sample of fluid comprising:

providing a device for sampling a fluid, comprising a pre-chamber having an interior surface and being capable of exerting a first capillary force, a sensing chamber in fluid communication with the pre-chamber, the sensing chamber having an interior surface and being capable of exerting a second capillary force;

wherein a differential exist between the capillary forces, the differential being sufficient to cause flow of fluid from the pre-chamber to the sensing chamber, and wherein the pre-chamber further comprises a volume such that when full the pre-chamber comprises at least as much sample as is needed to substantially fill the sensing chamber;

contacting the device with the fluid for a sufficient period of time to allow the fluid to enter the pre-chamber; and

allowing the sample to flow from the pre-chamber to the sensing chamber, such that the sensing chamber is substantially filled.

16. The method of claim 15, wherein the sensing chamber comprises electrodes capable of use in an electrochemical cell.

17. The method of claim 16, wherein the electrodes are spaced apart by a distance of 600 microns or less.

18. The method of claim 16, wherein the electrodes are spaced apart by a distance of 400 microns or less.

19. The method of claim 16, wherein the electrodes are spaced apart by a distance of 200 microns or less.

20. The method of claim 15, the sensing chamber further comprising a chemical for use in the sensing chamber.

21. The method of claim 20, the chemical further comprising a reagent capable of undergoing a redox reaction with an analyte or a reaction product of the analyte.

22. The method of claim 15, further comprising the step of:

detecting a condition wherein the pre-chamber contains a volume of fluid sufficient to substantially fill the sensing chamber.

23. The method of claim 15, further comprising the step of:

determining a presence or an absence of an analyte in the sample.

24. The method of claim 23, wherein the determining step comprises conducting a quantitative measurement of the analyte.

25. The method of claim 23, wherein the determining step comprises an electrochemical measurement.

26. The method of claim 23, wherein the analyte comprises a substance selected from the group consisting of lactate, cholesterol, enzymes, nucleic acids, lipids, polysaccharides, and metabolites.

27. The method of claim 23, wherein the analyte comprises glucose.

28. The method of claim 23, wherein the sample comprises a biological fluid.

29. The method of claim 28, wherein the biological fluid comprises a body fluid of an animal or a plant.

30. The method of claim 29, wherein the body fluid is selected from the group consisting of interstitial fluid, blood, tears, expectorate, saliva, urine, semen, vomitus, sputum, fruit juice, vegetable juice, plant sap, and nectar.

31. The method of claim 28, wherein the biological fluid comprises a food product.

32. The method of claim 23, wherein the sample comprises a non-biological fluid.

33. The method of claim 32, wherein the non-biological fluid comprises a water-based solution.

34. The method of claim 15, 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 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.

35. The method of claim 15, wherein the interior surface of the pre-chamber having a first surface roughness, as 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 is defined as the actual surface area divided by the geometric surface area.