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:
- an electrode pair comprising a first electrode and a second electrode, wherein the first electrode and second electrode are separated by an effective distance in a range of 25 to 1000 μ
m;
a first substrate having a proximal end and a distal end, the first substrate defining a first side edge and a second side edge of the electrochemical sensor extending from the proximal end to the distal end of the first substrate, the distal end being configured and arranged for insertion into a sensor reader;
a second substrate disposed over the first substrate, the first electrode being disposed on the first substrate and the second electrode being disposed on the second substrate;
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 the first side edge of the sensor and a second aperture along the second side edge of the sensor, wherein either the first aperture or the second aperture are 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 the sample fluid, 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
an analyte-responsive enzyme and a diffusible redox mediator disposed in the sample chamber.
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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.
466 Citations
46 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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an electrode pair comprising a first electrode and a second electrode, wherein the first electrode and second electrode are separated by an effective distance in a range of 25 to 1000 μ
m;a first substrate having a proximal end and a distal end, the first substrate defining a first side edge and a second side edge of the electrochemical sensor extending from the proximal end to the distal end of the first substrate, the distal end being configured and arranged for insertion into a sensor reader; a second substrate disposed over the first substrate, the first electrode being disposed on the first substrate and the second electrode being disposed on the second substrate; 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 the first side edge of the sensor and a second aperture along the second side edge of the sensor, wherein either the first aperture or the second aperture are 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 the sample fluid, 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; andan analyte-responsive enzyme and a diffusible redox mediator disposed in the sample chamber. - 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, 26, 27, 28, 29)
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30. A method for determining a concentration of an analyte in a sample, comprising the steps of:
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contacting a sample with a sensor, wherein the sensor comprises; an electrode pair comprising a first electrode and a second electrode, wherein the first electrode and second electrode are separated by an effective distance in a range of 25 to 1000 μ
m;a first substrate having a proximal end and a distal end, the first substrate defining a first side edge and a second side edge of the electrochemical sensor extending from the proximal end to the distal end of the first substrate, the distal end being configured and arranged for insertion into a sensor reader; a second substrate disposed over the first substrate, the first electrode being disposed on the first substrate and the second electrode being disposed on the second substrate; 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 the first side edge of the sensor and a second aperture along the second side edge of the sensor, wherein either the first aperture or the second aperture are 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 the sample fluid, 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; andan analyte-responsive enzyme and a diffusible redox mediator disposed in the sample chamber; generating a sensor signal at the first electrode, and determining the concentration of the analyte using the sensor signal. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. A method for determining a concentration of an analyte in a sample, the method comprising the steps of:
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contacting a sample with a sensor, wherein the sensor comprises; an electrode pair comprising a first electrode and a second electrode, wherein the first electrode and second electrode are separated by an effective distance in a range of 25 to 1000 μ
m;a first substrate having a proximal end and a distal end, the first substrate defining a first side edge and a second side edge of the electrochemical sensor extending from the proximal end to the distal end of the first substrate, the distal end being configured and arranged for insertion into a sensor reader; a second substrate disposed over the first substrate, the first electrode being disposed on the first substrate and the second electrode being disposed on the second substrate; 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 the first side edge of the sensor and a second aperture along the second side edge of the sensor, wherein either the first aperture or the second aperture are 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 the sample fluid, 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; andan analyte-responsive enzyme and a diffusible redox mediator disposed in the sample chamber; observing a signal from an indicator electrode to signify that the sample chamber contains sample; applying a potential between the first electrode and the second electrode to electrolyze the analyte in the sample; generating an analyte-responsive signal from the sensor in response to electrolysis of the analyte in the sample; and determining the concentration of the analyte using the analyte-responsive signal.
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Specification