Small volume in vitro sensor and methods of making
First Claim
1. A sensor for determining the concentration of glucose in a sample fluid, the sensor comprising:
- a working electrode and a counter electrode, wherein the working electrode and counter electrode are separated by an effective distance in a range of 25 to 1000 μ
m;
a sample chamber for holding the sample fluid, the sample chamber comprising the working electrode and the counter electrode, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample;
two indicator electrodes disposed in the sensor, wherein a first indicator electrode indicates when the sample chamber is beginning to fill with sample, and a second indicator electrode indicates when the sample chamber is substantially filled with sample, and wherein the working electrode is disposed between the first and second indicator electrodes; and
a glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, the sensor having been configured and arranged so that a background signal generated by the diffusible redox mediator is no more than the signal generated by oxidation or reduction of 80 mg/dL of glucose.
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Accused Products
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.
468 Citations
30 Claims
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1. A sensor for determining the concentration of glucose in a sample fluid, the sensor comprising:
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a working electrode and a counter electrode, wherein the working electrode and counter electrode are separated by an effective distance in a range of 25 to 1000 μ
m;a sample chamber for holding the sample fluid, the sample chamber comprising the working electrode and the counter electrode, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample;two indicator electrodes disposed in the sensor, wherein a first indicator electrode indicates when the sample chamber is beginning to fill with sample, and a second indicator electrode indicates when the sample chamber is substantially filled with sample, and wherein the working electrode is disposed between the first and second indicator electrodes; and a glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, the sensor having been configured and arranged so that a background signal generated by the diffusible redox mediator is no more than the signal generated by oxidation or reduction of 80 mg/dL of glucose. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A sensor for determining the concentration of glucose in a sample fluid, the sensor comprising:
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a sample chamber for holding the sample fluid, the sample chamber comprising a working electrode, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample;a first electrode and a second electrode disposed in the sample chamber and flanking the working electrode, wherein the first electrode indicates when the sample chamber is beginning to fill with sample, and the second electrode indicates when the sample chamber is substantially filled with sample; and a glucose-responsive enzyme and a redox mediator disposed in the sample chamber. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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Specification