Small volume in vitro analyte sensor and methods of making
First Claim
1. A coulometric 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, the counter electrode, a first indicator electrode to indicate when the sample chamber is beginning to fill with sample, and a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample; and
a glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, wherein a background signal generated by the diffusible redox mediator in the absence of glucose is no more than 25% of the signal generated by oxidation or reduction of 80 mg/dL of glucose.
2 Assignments
0 Petitions
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.
-
Citations
24 Claims
-
1. A coulometric 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, the counter electrode, a first indicator electrode to indicate when the sample chamber is beginning to fill with sample, and a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample; anda glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, wherein a background signal generated by the diffusible redox mediator in the absence of glucose is no more than 25% of 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. A method for determining a concentration of glucose in a sample, comprising the steps of:
-
contacting a sample with a sensor, wherein the sensor comprises; 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, the counter electrode, a first indicator electrode to indicate when the sample chamber is beginning to fill with sample, and a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample; anda glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, wherein a background signal generated by the diffusible redox mediator in the absence of glucose is no more than 25% of the signal generated by oxidation or reduction of 80 mg/dL of glucose; generating a sensor signal at the working electrode, and determining the concentration of the glucose by coulometry using the sensor signal. - View Dependent Claims (22, 23)
-
-
24. A method for determining a concentration of glucose in a sample, the method comprising the steps of:
-
contacting a sample with a sensor, wherein the sensor comprises; 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, the counter electrode, a first indicator electrode to indicate when the sample chamber is beginning to fill with sample, and a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein the sample chamber is sized to contain a volume of no more than about 1 μ
L of the sample; anda glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, wherein a background signal generated by the diffusible redox mediator in the absence of glucose is no more than 25% of the signal generated by oxidation or reduction of 80 mg/dL of glucose; observing a signal from the second indicator electrode to signify that the sample chamber is substantially filled with sample; applying a potential between the working electrode and the counter electrode to electrolyze the glucose in the sample; generating a glucose-responsive signal from the sensor in response to electrolysis of the glucose in the sample; and determining the concentration of the glucose by coulometry using the glucose-responsive signal.
-
Specification