Small volume in vitro analyte sensor and methods of making
First Claim
1. A sensor for determining the concentration of an analyte in a sample fluid, the sensor comprising:
- a proximal end and a distal end, the distal end being configured and arranged for insertion into a sensor reader, and the proximal end comprising first and second extensions on a first and second side edge of the sensor;
an electrode pair 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;
a first indicator electrode to indicate when the sample chamber is beginning to fill with sample;
a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein either the working electrode or the counter electrode is disposed between the first and second indicator electrodes; and
an analyte-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 in the absence of the analyte is no more than 25% of the signal generated by oxidation or reduction of the average normal physiological amount of analyte.
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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.
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Citations
25 Claims
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1. A sensor for determining the concentration of an analyte in a sample fluid, the sensor comprising:
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a proximal end and a distal end, the distal end being configured and arranged for insertion into a sensor reader, and the proximal end comprising first and second extensions on a first and second side edge of the sensor; an electrode pair 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;a first indicator electrode to indicate when the sample chamber is beginning to fill with sample; a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein either the working electrode or the counter electrode is disposed between the first and second indicator electrodes; and an analyte-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 in the absence of the analyte is no more than 25% of the signal generated by oxidation or reduction of the average normal physiological amount of analyte. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification