Small volume in vitro analyte sensor and methods of making

• US 8,182,670 B2
• Filed: 09/29/2009
• Issued: 05/22/2012
• Est. Priority Date: 10/08/1998
• Status: Expired due to Fees

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories)
• Inventors: Feldman, Benjamin J., Heller, Adam, Mao, Fei, Vivolo, Joseph A., Funderburk, Jeffery V., Krishnan, Rajesh, Heller, Ephraim, Colman, Fredric C.
• Primary Examiner(s): Noguerola, Alex
• Application Number:
  US12/569,164
• Publication Number:
  US 20100018872A1
• Time in Patent Office: 966 Days
• Field of Search: 20440301-40315, 205/777.5, 205/778, 205/792
• US Class Current: 205/792
• 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 for determining a concentration of a ketone in a sample, comprising the steps of:

contacting a sample with a sensor, wherein the sensor comprises;

a first electrode, a second electrode, and a third electrode;

a sample chamber for holding the sample fluid, the sample chamber comprising the first electrode, the second electrode, and the third electrode, wherein the first electrode is positioned upstream of the second electrode relative to a sample entry port and the third electrode is positioned downstream of the second electrode relative to the sample entry port; and

an ketone-responsive enzyme and a redox mediator disposed in the sample chamber;

determining when the sample contacts the first electrode and the second electrode;

determining when the sample contacts the first electrode and the third electrode;

applying a potential between the first and second electrodes to electrolyze the ketone, thereby generating a ketone signal; and

determining the concentration of the ketone using the ketone signal.

2. The method according to claim 1, wherein determining when the sample contacts the first electrode and the second electrode comprises observing a signal between the first and second electrodes.

3. The method according to claim 2, wherein observing a signal between the first and second electrodes comprises observing a voltage, current, resistance, impedance, capacitance, or combination thereof between the first and second electrodes.

4. The method according to claim 1, wherein determining when the sample contacts the first electrode and the third electrode comprises observing a signal between the first and third electrodes.

5. The method according to claim 4, wherein observing a signal between the first and third electrodes comprises observing a voltage, current, resistance, impedance, capacitance, or combination thereof between the first and third electrodes.

6. The method according to claim 1, wherein determining the concentration of the ketone comprises determining the concentration of the ketone by coulometry using the ketone signal.

7. The method according to claim 1, wherein determining the concentration of the ketone comprises determining the concentration of the ketone by amperometry using the ketone signal.

8. The method according to claim 1, wherein determining the concentration of the analyte comprises determining the concentration of the analyte by potentiometry using the ketone signal.

9. The method according to claim 1, further comprising:

providing calibration data on a batch of the electrochemical sensors to a measurement instrument, said calibration data comprising information related to a magnitude of a background charge for the batch of the electrochemical sensors;

wherein the step of determining the concentration of the ketone comprises determining the concentration of the ketone using the ketone signal and the calibration data.

10. The method according to claim 1, wherein the sensor is configured and arranged so that a background signal generated by the redox mediator is no more than 25% of the signal generated by oxidation or reduction of the ketone.

11. The method according to claim 1, wherein the sensor is configured and arranged so that a background signal generated by the redox mediator is no more than 10% of the signal generated by oxidation or reduction of the ketone.

12. The method according to claim 1, wherein the sample chamber is sized to contain a volume of no more than about 1 μ

L of the sample.

13. The method according to claim 1, wherein the first, second and third electrodes are coplanar.

14. The method according to claim 1, wherein the sensor is a tip-fill sensor.

15. The method according to claim 1, wherein the sample is a blood sample, and wherein the method further comprises obtaining the blood sample from a finger of a subject.

16. The method according to claim 1, wherein the sample is a blood sample, and wherein the method further comprises obtaining the blood sample from a region of a subject having a lower nerve end density as compared to a fingertip.

17. The method according to claim 16, wherein the region of a subject having a lower nerve end density as compared to a fingertip is selected from the group consisting of:

a forearm region, and a thigh region.