Photoresponsive electrode for determination of redox potential

A field effect device for determining the state of a medium in relation to a redox potential standard, said device comprising:

• a detection element comprising a base semiconductor layer, an insulating layer covering at least a portion of a surface of said semiconductor layer, a metal layer mounted on said insulative layer or said base layer at the exposed portion of said surface, said metal layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said medium contacting surface;
• irradiation means for irradiating said irradiation receiving surface to produce a photoinduced signal;
• means, connected to said detection element, for polarizing said detection element;
• holding means for retaining one or more media in which determinations are to be made in contact with said medium contacting surface;
• and
• a circuit for measuring the change in photoinduced electrical signal from said detection element as a result of the redox potential of a medium, wherein said circuit includes a high resistance element when said metal layer is in contact with said base layer.

A field effect device for determining the state of an assay medium in relation to a pH, ion concentration or redox potential standard, said device comprising:

• a detection element comprising a base semiconductor layer, an intermediate insulating layer covering at least a portion of said surface of said semiconductive layer, a metal layer mounted on and covering only a portion of said insulative layer, each of said metal layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said medium contacting surface;
• irradiation means for irradiating said irradiation receiving surface to provide a photoinduced signal;
• means, connected to said detection element, for polarizing said element;
• holding means for retaining one or media in which determinations are to be made in contact with said medium contacting surface;
• and
• a circuit for measuring the change in a photoinduced electrical signal from said detection element as a result of a change in the redox potential, an ion concentration and/or pH of a medium.

A field effect device for making a determination in relation to a variable system and adjusting said variable system determination in relation to a determination made in relation to a constant system, wherein one of said systems is a redox system and the other system is a pH or ion concentration system, said device employing a photoinduced signal as a result of irradiation of a photoresponsive element, said device comprising:

• a detection element comprising a base semiconductor layer, an insulating layer covering at least a portion of a surface of said semiconductor layer, a metal layer mounted on and covering only a portion of said insulative layer or on said semiconductor layer surface at an uncovered portion, each of said metal layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said metal layer and said insulative layer, wherein said metal layer is for obtaining a redox related signal and said insulative layer is for obtaining a pH or ion concentration related signal;
• a counterelectrode;
• irradiation means for irradiating said irradiation receiving surface to produce a photoinduced signal;
• polarizing means, connected to said detection element, for polarizing said detection element;
• holding means for retaining one or more media in which determinations are to be made in contact with said medium contacting surfaces;
• a circuit connecting said detection element and counterelectrode for measuring the change in photoinduced electrical signal from said detection element as a result of the redox potential of a medium and as a result of the pH or an ion concentration of a medium, for determining a relationship between the signal from the variable system and the signal from said constant system.

A method for measuring a state of a medium, wherein said state may be related directly or indirectly to redox potential, pH, or an ion concentration, wherein redox potential and one other state is measured, and one of said redox potential, pH, or ion concentration is a variable system of interest and the other is a constant system, said method employing a device comprising:

• a detection element comprising a base semiconductor layer, an intermediate insulating layer covering at least a portion of a surface of said semiconductive layer, a metal layer mounted on and covering only a portion of said insulative layer, each of said metal layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said medium contacting surfaces, wherein said metal layer is for obtaining a redox related signal and said insulative layer is for obtaining a pH or ion related signal;
• an irradiation means for irradiating said irradiation receiving surface to produce a photoinduced signal;
• a counterelectrode;
• a circuit connecting said detection element and said counterelectrode;
• a holding means for retaining a medium in electrical contact with said detection element and said counterelectrode;
• said method comprising:
• introducing said medium to provide electrical communication between said detection element and said counterelectrode;
• irradiating said irradiation receiving surface to produce a photoinduced signal:
• determining the photoinduced signal from the constant system as compared to the signal related to the variable system, and relating the difference in said signals to the state of said medium as to said variable system.

A method for measuring an analyte in a sample, said analyte capable of reacting directly or indirectly with a redox modulating system which comprises a redox couple, said measuring comprising measuring the change in the redox potential of a sample containing medium employing a device comprising:

• a detection element comprising a base semiconductor layer, an intermediate insulating layer covering at least a portion of a surface of said semiconductive layer, a metal layer mounted on and covering only a portion of said insulative layer, each of said metal layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said medium contacting surfaces, wherein said metal layer is for obtaining a redox related signal and said insulative layer is for obtaining a pH related signal or ion related signal;
• and a counterelectrode;
• said method comprising:
• introducing said medium to provide electrical communication between said detection element and said counterelectric and to provide an assay medium, wherein said assay medium comprises said sample, a redox modulating system capable of reacting directly or indirectly with said analyte, and sufficient buffer to maintain a constant pH or sufficient ion to maintain a constant ion concentration;
• irradiating said irradiation receiving surface to produce a photoinduced signal;
• determining said pH related or ion related photoinduced signal as compared to said redox related photoinduced signal and standardizing the difference between said pH or ion related photoinduced signal and said redox related photoinduced signal, wherein said difference is related to a known amount of analyte.

A method for measuring a glucose containing sample by means of measuring the change in the redox potential of a sample containing medium employing a device comprising:

• a detection element comprising a base semiconductor layer, an intermediate insulating layer covering at least a portion of a surface of said semiconductive layer, a metal layer mounted on and covering only a portion of said insulative layer, each of said metal layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said medium contacting surfaces, wherein said metal layer is for obtaining a redox related signal and said insulative layer is for obtaining a pH related signal or ion related signal;
• said method comprising:
• introducing said medium to provide electrical communication between said detection element and said counterelectrode and to provide an assay medium, wherein said assay medium comprises said sample, glucose oxidase, glucose, a redox system capable of reacting with hydrogen peroxide and communicating the redox potential to said metal layer, and sufficient buffer to maintain a substantially constant pH;
• irradiating said irradiation receiving surface to produce a photoinduced signal;
• determining said pH related signal as compared to said redox related signal and standardizing the rate of change in the difference between said pH related signal and said redox potential related signal to a known amount of glucose.

A method for measuring the amount of analyte in a sample by measuring the redox potential of a sample containing medium employing a device comprising:

• detection element comprising a base semiconductor layer, an intermediate insulating layer covering at least a portion of a surface of said semiconductive layer, a metal layer mounted on and covering only a portion of said insulative layer, each of said metal layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in juxtaposition to said medium contacting surfaces, wherein said metal layer is for obtaining a redox related signal and said insulative layer is for obtaining a pH or ion related signal;
• and a counterelectrode;
• and
• a member of a specific binding pair nondiffusively bound in juxtaposition to said metal layer or said insulative layer;
• said method comprising:
• introducing said medium to provide electrical communication between said detection element and said counterelectrode to provide an assay medium, wherein said assay medium comprises, a redox modulating system comprising an oxidoreductase-specific binding pair member conjugate, a redox couple, oxidoreductase substrate and any cofactors, and wherein the total oxidoreductase reaction rate in said medium is related to the amount of analyte in said sample;
• irradiating said irradiation receiving surface to produce a photoinduced signal;
• determining said pH or ion related signal as compared to said redox related signal and relating the difference between said pH or ion related signal and said redox related signal to the amount of analyte in said sample.

A method of measuring a state of a medium by an amperometric measurement, wherein said state may be related directly or indirectly to redox potential, pH, or an ion concentration, wherein redox potential and one other state is measured, and one of said redox potential, pH, or ion concentration is a variable system of interest and the other is a constant system, said method employing a device comprising:

• a detection element comprising a base semiconductor layer, an intermediate insulating layer covering only a portion of a surface of said semiconductor layer, a electronically conductive layer mounted on said surface at an uncovered portion of said surface, each of said electronically conductive layer and insulative layer having a medium contacting surface and said base layer having an irradiation receiving surface for forming minority carriers in a region in juxtaposition to said medium contacting surfaces, said region being reverse biased, wherein said electronically conductive layer is for obtaining a Faradaic current and said insulative layer is for obtaining a pH or ion related signal;
• a counterelectrode;
• a circuit connecting said detection element and said counterelectrode;
• a holding means for retaining a medium in electrical contact with said detection element and said counterelectrode;
• said method comprising:
• introducing said medium to provide electrical communication between said detection element and said counterelectrode;
• irradiating said irradiation receiving surface to produce a photoinduced signal:
• determining the photoinduced signal from the constant system and determining the resulting photoinduced amperometric signal related to the variable system, and relating said amperometric signal to the state of said medium.