Method of manufacturing small volume in vitro analyte sensor

• US 6,618,934 B1
• Filed: 06/15/2000
• Issued: 09/16/2003
• Est. Priority Date: 10/08/1998
• Status: Expired due to Term

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories)
• Original Assignee: Therasense Incorporated (Abbott Laboratories)
• Inventors: Krishnan, Rajesh, Heller, Ephraim, Heller, Adam, Colman, Fredric C., Feldman, Benjamin J., Mao, Fei, Funderburk, Jeffery V., Vivolo, Joseph A.
• Primary Examiner(s): Vo, Peter
• Assistant Examiner(s): NGUYEN, DONGHAI D
• Application Number:
  US09/594,285
• Time in Patent Office: 1,188 Days
• Field of Search: 295/73, 295/74, 295/95, 298/30, 298/74, 298/76, 298/77, 298/84, 600/345, 600/346, 600/347, 600/504, 205/777.5, 264/403.01, 264/403.03, 264/403.04, 264/403.14, 264/409, 264/416, 427/2.13, 435/287.5, 435/287.8, 435/287.9
• US Class Current: 29/830
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: C12Q 1/32 involving dehydrogenase
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49147 Assembling terminal to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49204 Contact or terminal manufacturing
• CPC Class Codes: Y10T 29/49208 by assembling plural parts
• CPC Class Codes: Y10T 29/4921 with bonding
• CPC Class Codes: Y10T 29/49794 Dividing on common outline

Abstract

A sensor utilizing a non-leachable or diffusible redox mediator is described. The sensor includes a sample chamber to hold a sample in electrolytic contact with a working electrode, and in at least some instances, the sensor also contains a non-leachable or a diffusible second electron transfer agent. The sensor and/or the methods used produce a sensor signal in response to the analyte that can be distinguished from a background signal caused by the mediator. The invention can be used to determine the concentration of a biomolecule, such as glucose or lactate, in a biological fluid, such as blood or serum, using techniques such as coulometry, amperometry, and potentiometry. An enzyme capable of catalyzing the electrooxidation or electroreduction of the biomolecule is typically provided as a second electron transfer agent.

Claims

1. A method of manufacturing a plurality of electrochemical sensors, the method comprising the steps of:

(a) forming a plurality of working electrodes on a first electrode region of a substrate;

(b) forming a plurality of counter electrodes on a second electrode region of the substrate;

(c) disposing a spacer layer on one of the first and the second electrode regions;

(d) removing a portion of the spacer layer to define sample chamber regions;

(e) folding the substrate with the spacer layer between the first electrode region and the second electrode region to form a layered structure; and

(f) separating the layered structure into a plurality of electrochemical sensors, each electrochemical sensor comprising at least one working electrode, at least one counter electrode, and at least one sample chamber region.

2. A method of manufacturing a plurality of electrochemical sensors, the method comprising the steps of:

(a) forming a plurality of working electrodes on a first electrode region of a first substrate;

(b) forming a plurality of counter electrodes on a second electrode region of the first substrate;

(c) disposing a spacer layer on one of the first electrode region and the second electrode region, the spacer layer defining sample chamber regions;

(d) folding the substrate with the spacer layer between the first electrode region and the second electrode region to form a layered structure; and

(e) cutting the layered structure to provide individual electrochemical sensors, each electrochemnical sensor comprising at least one working electrode, at least one counter electrode, and at least one sample chamber region, wherein at least one end of the at least one sample chamber region is defined by a cut.

3. A method of manufacturing electrochemical sensors, the method comprising the steps of:

(a) forming a plurality of working electrodes on a first region of a first substrate, the working electrodes comprising a material selected from the group consisting of gold, carbon, platinum, ruthenium dioxide, and palladium;

(b) forming a plurality of counter electrodes on a second region of the first substrate, the counter electrodes comprising a material selected from the group consisting of gold, carbon, platinum, ruthenium dioxide, and palladium;

(c) disposing a spacer layer overlaying the working and counter electrodes, the spacer layer having a thickness of no more than 0.2 mm;

(d) removing a portion of the spacer layer to define a portion of a boundary for a sample chamber;

(e) overlaying the first substrate and the spacer layer with a second substrate to form a layered structure; and

(f) separating the layered structure into a plurality of electrochemical sensors, each electrochemical sensor comprising;

(i) at least one working electrode having a working area of no more than about 0.01 cm²,

(ii) at least one counter electrode, wherein each at least one working electrode is spaced from each at least one counter electrode by 25-1000 micrometers, and

(iii) at least one sample chamber having a volume less than 1 microliter and including a circular recess having al least a portion of the working electrode and a diffusible redox mediator situated in the recess.

4. The method according to claim 3, wherein the step of disposing a spacer layer is done prior to the step of removing a portion of the spacer layer to define a portion of a boundary for a sample chamber.

5. The method according to claim 3, wherein the step of removing a portion of the spacer layer to define a portion of a boundary for a sample chamber is done prior to the step of disposing a spacer layer.

6. The method according to claim 3, wherein the step of disposing a spacer layer comprises:

(a) disposing a spacer layer having a thickness of no more than 0.1 mm.

7. The method according to claim 3, further comprising

(a) forming a plurality of indicator electrodes on the substrate;

and

(b) wherein the step of separating the layered structure into a plurality of electrochemical sensors comprises;

(i) separating the layered structure into a plurality of electrochemical sensors, each electrochemical sensor comprising at least one working electrode, at least one counter electrode, at least one indicator electrode, and at least one sample chamber.

8. The method according to claim 3, where the step of forming a plurality of working electrodes comprises:

(a) printing a plurality of working electrodes; and

wherein the step of forming a plurality of counter electrodes comprises;

(b) printing a plurality of counter electrodes.

9. The method according to claim 8, wherein:

(a) the step of printing a plurality of working electrodes comprises;

(i) printing a carbon ink; and

(b) the step of printing a plurality of counter electrodes comprises;

(i) printing a Ag/AgCl ink.

10. The method according to claim 3, wherein the step of separating the layered structure into a plurality of electrochemical sensors comprises:

(a) die cutting the layered structure to form the plurality of electrochemical sensors.

11. The method according to claim 3, wherein the step of separating the layered structure into a plurality of electrochemical sensors comprises:

(a) slitting the layered structure to form the plurality of electrochemical sensors.

12. The method according to claim 3, wherein the substrate has a length and a width, and wherein:

(a) the step of forming a plurality of working electrodes on a first region of the substrate comprises;

(i) forming a plurality of working electrodes on the first substrate in the first region having a length and a width;

the plurality of working electrodes arranged in columns parallel to the width of the substrate and in rows parallel to the length of the substrate; and

(b) the step of forming a plurality of counter electrodes on a second region of the substrate comprises;

(i) forming a plurality of counter electrodes in the second region having a length and a width;

the plurality of counter electrodes arranged in columns parallel to the width of the second substrate and in rows parallel to the length of the substrate.

13. The method according to claim 3, fiber comprising:

(a) depositing an enzyme over a portion of the working electrodes or the counter electrodes.

14. The method according to claim 13, further comprising:

(a) depositing an enzyme continuously over a portion of at least two of the working electrodes or at least two of the counter electrodes.

15. The method according to claim 3, further comprising:

(a) depositing a redox mediator over a portion of the working electrodes or the counter electrodes.

16. The method according to claim 15, further comprising:

(a) depositing a redox mediator continuously over a portion of at least two of the working electrodes or two of the counter electrodes.

17. The method according to claim 3, wherein the step of forming a plurality of working electrodes comprises:

(a) forming a plurality of working electrodes from a carbon ink; and

wherein the step of forming a plurality of counter electrodes comprises;

(b) forming a plurality of counter electrodes of a Ag/AgCl ink.

18. The method according to claim 3, wherein the step of forming a plurality of working electrodes comprises:

(a) forming a plurality of working electrodes from a material comprising gold; and

wherein the step of forming a plurality of counter electrodes comprises;

(b) forming a plurality of counter electrodes from a material comprising gold.

19. The method according to claim 3, wherein the step of separating the layered structure into a plurality of electrochemical sensors comprises:

(a) separating the layered structure into a plurality of electrochemical sensors, each electrochemical sensor comprising;

(i) at least one sample chamber having a volume less than 0.5 microliter.

20. The method according to claim 19, wherein the step of separating the layered structure into a plurality of electrochemical sensors comprises:

(a) separating the layered structure into a plurality of electrochemical sensors, each electrochemical sensor comprising;

(i) at least one sample chamber having a volume less than 0.1 microliter.

21. The method according to claim 3, wherein the step of disposing a spacer layer overlaying the working and counter electrodes comprises:

(a) disposing an adhesive spacer layer having a thickness no more than 0.1 mm.

22. A method of manufacturing electrochemical sensors, the method comprising the steps of:

(a) forming a plurality of working electrodes on a first region of a first substrate, the working electrodes comprising gold;

(b) forming a plurality of counter electrodes on a second region of the first substrate, the counter electrodes comprising gold;

(c) disposing a spacer overlaying the working and counter electrodes, the spacer having a thickness of no more than 0.2 mm;

(d) removing a portion of the spacer to define a portion of a boundary for a sample chamber;

(c) overlaying the first substrate and the spacer with a second substrate to form a layered structure; and

(f) separating the layered structure into a plurality of electrochemical sensors, each electrochemical sensor comprising;

(i) a sample chamber including at least one working electrode having a working area of no more than about 0.01 cm² formed within a circular recess therein, the sample chamber including a diffusible redox mediator and having a volume less than 1 microliter; and

(ii) at least one counter electrode, each at least one working electrode spaced from each at least one counter electrode by 25-1000 micrometers.

23. The method according to claim 22, wherein the step of disposing a spacer is done prior to the step of removing a portion of the spacer.

24. The method according to claim 22, wherein the step of removing a portion of the spacer is done prior to the step of disposing the spacer.

25. The method according to claim 22, wherein the step of disposing a spacer comprises:

(a) disposing a spacer having a thickness of no more than 0.1 mm.

26. The method according to claim 22, where the step of forming a plurality of working electrodes comprises:

(a) printing a plurality of working electrodes.

27. The method according to claim 22, further comprising:

(a) depositing an enzyme over a portion of the working electrodes or the counter electrodes.

28. The method according to claim 22, further comprising:

(a) depositing an enzyme continuously over a portion of at least two of the working electrodes or at least two of the counter electrodes.

29. The method according to claim 22, where the sample chamber has a volume of no more than about 0.5 microliters.

30. The method according to claim 29, where the sample chamber has a volume of no more than about 0.25 microliters.

31. The method according to claim 22, wherein the step of separating the layered structure into a plurality of electrochemical sensors comprises:

(a) slitting the layered structure.