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 disposed on a first substrate and a counter/reference electrode disposed on a second substrate, wherein the working electrode comprises palladium and the counter/reference electrode comprises gold, and wherein the working electrode and the counter/reference electrode are in a facing configuration and separated by an effective distance in a range of 25 to 1000 μ
m;
a spacer comprising a first part and a second part disposed between the first and second substrates, wherein the first part of the spacer, the second part of the spacer, the first substrate, and the second substrate define a first aperture along a first side edge of the sensor and a second aperture along a second side edge of the sensor, wherein either the first aperture or the second aperture is used for sample application and the sensor has no more than two apertures;
a sample chamber for holding the sample fluid and sized to contain a volume of no more than about 1 μ
L of sample, wherein the sample chamber has a length which extends from the first aperture to the second aperture and a substantially uniform width between the first part of the spacer and the second part of the spacer along the entire length of the sample chamber, and wherein the width of the sample chamber is not wider than either the first aperture or the second aperture; and
a glucose dehydrogenase and a diffusible redox mediator comprising ferricyanide disposed in the sample chamber;
wherein the first and second substrates define a sensor comprising a proximal end having a width and a distal end having a width, the distal end being configured for insertion into a sensor reader, wherein the width of the distal end is greater than the width of the proximal end.
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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
46 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 disposed on a first substrate and a counter/reference electrode disposed on a second substrate, wherein the working electrode comprises palladium and the counter/reference electrode comprises gold, and wherein the working electrode and the counter/reference electrode are in a facing configuration and separated by an effective distance in a range of 25 to 1000 μ
m;a spacer comprising a first part and a second part disposed between the first and second substrates, wherein the first part of the spacer, the second part of the spacer, the first substrate, and the second substrate define a first aperture along a first side edge of the sensor and a second aperture along a second side edge of the sensor, wherein either the first aperture or the second aperture is used for sample application and the sensor has no more than two apertures; a sample chamber for holding the sample fluid and sized to contain a volume of no more than about 1 μ
L of sample, wherein the sample chamber has a length which extends from the first aperture to the second aperture and a substantially uniform width between the first part of the spacer and the second part of the spacer along the entire length of the sample chamber, and wherein the width of the sample chamber is not wider than either the first aperture or the second aperture; anda glucose dehydrogenase and a diffusible redox mediator comprising ferricyanide disposed in the sample chamber; wherein the first and second substrates define a sensor comprising a proximal end having a width and a distal end having a width, the distal end being configured for insertion into a sensor reader, wherein the width of the distal end is greater than the width of the proximal end. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for determining a concentration of a glucose in a sample, comprising the steps of:
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contacting a sample with an electrochemical sensor comprising; a working electrode disposed on a first substrate and a counter/reference electrode disposed on a second substrate, wherein the working electrode comprises palladium and the counter/reference electrode comprises gold, and wherein the working electrode and the counter/reference electrode are in a facing configuration and separated by an effective distance in a range of 25 to 1000 μ
m;a spacer comprising a first part and a second part disposed between the first and second substrates, wherein the first part of the spacer, the second part of the spacer, the first substrate, and the second substrate define a first aperture along a first side edge of the sensor and a second aperture along a second side edge of the sensor, wherein either the first aperture or the second aperture is used for sample application and the sensor has no more than two apertures; a sample chamber for holding the sample fluid and sized to contain a volume of no more than about 1 μ
L of sample, wherein the sample chamber has a length which extends from the first aperture to the second aperture and a substantially uniform width between the first part of the spacer and the second part of the spacer along the entire length of the sample chamber, and wherein the width of the sample chamber is not wider than either the first aperture or the second aperture; anda glucose dehydrogenase and a diffusible redox mediator comprising ferricyanide disposed in the sample chamber; generating a sensor signal at the working electrode, and determining the concentration of the glucose using the sensor signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A sensor for determining the concentration of glucose in a sample fluid, the sensor comprising:
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a working electrode disposed on a first substrate and a counter/reference electrode disposed on a second substrate, wherein the working electrode comprises palladium and the counter/reference electrode comprises gold, and wherein the working electrode and the counter/reference electrode are in a facing configuration and separated by an effective distance in a range of 25 to 1000 μ
m;a spacer comprising a first part and a second part disposed between the first and second substrates, wherein the first part of the spacer, the second part of the spacer, the first substrate, and the second substrate define a first aperture along a first side edge of the sensor and a second aperture along a second side edge of the sensor, wherein either the first aperture or the second aperture is used for sample application and the sensor has no more than two apertures; a sample chamber for holding the sample fluid and sized to contain a volume of no more than about 1 μ
L of sample, wherein the sample chamber has a length which extends from the first aperture to the second aperture and a substantially uniform width between the first part of the spacer and the second part of the spacer along the entire length of the sample chamber, and wherein the width of the sample chamber is not wider than either the first aperture or the second aperture; anda glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber; wherein the first and second substrates define a sensor comprising a proximal end having a width and a distal end having a width, the distal end being configured for insertion into a sensor reader, wherein the width of the distal end is greater than the width of the proximal end. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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Specification