Implantable microelectronic biochemical sensor incorporating thin film thermopile

A sensor for providing an electrical voltage representative of the concentration of a chemical dissolved in a fluid, said sensor comprising in combination:

• a. a supporting substrate;
• b. a thin film thermopile disposed upon said supporting substrate, said thin film thermopile including a plurality of pairs of thin film thermocouple junctions disposed upon said supporting substrate, each of said pairs of thermocouple junctions including a reference junction and a sensing junction electrically coupled in series connection with one another and spaced apart form one another, said reference junction and said sensing junction within each pair of thin film thermocouple junctions creating a temperature-dependent voltage when said reference junction and said sensing junction are electrically coupled in series connection, said plurality of pairs of thermocouple junctions being electrically coupled in series connection with one another between first and second terminals;
• c. a layer of a substance disposed proximate to each of said sensing junctions, said substance facilitating chemical reactions involving said chemical dissolved in said fluid adjacent said sensing junctions but not adjacent said reference junctions;
• d. wiring means coupled to said first and second terminals of said plurality of pairs of thin film thermocouple junctions for providing a voltage difference signal proportional to a difference in temperatures proximate the sensing and reference junctions arising from chemical reactions facilitated by said substance;
• and
• e. a catheter having a tip for insertion within a human body, said supporting substrate being secured within said tip of said catheter for being inserted within a human body to measure the concentration of a chemical within body fluid.

A sensor for providing an electrical voltage representative of the concentration of a chemical dissolved in a fluid, said sensor operating substantially independently of the absolute temperature of said fluid, said sensor comprising in combination:

• a. a supporting substrate;
• b. a thin film thermopile disposed upon said supporting substrate, said thin film thermopile including a plurality of pairs of thin film thermocouple junctions, each of said pairs of thermocouple junctions including a reference junction and a sensing junction electrically coupled in series connection with one another and spaced apart from one another, said reference junction and said sensing junction within each pair of thin film thermocouple junctions each creating a temperature-dependent voltage, each such pair of thermocouple junctions creating an electrical potential proportional in magnitude to the temperature difference between the reference junction and the sensing junction thereof, said plurality of pairs of thermocouple junctions being electrically coupled in series connection with one another between first and second terminals to multiply the electrical potential difference created by each such pair of thin film thermocouple junctions;
• c. a layer of a substance disposed proximate to each of said sensing junctions but not overlying the reference junctions, said substance facilitating chemical reactions involving said chemical dissolved in said fluid adjacent said sensing junctions but not adjacent said reference junctions;
• and
• d. wiring means coupled to said first and second terminals of said thin film thermopile for providing a voltage difference signal proportional to the difference between the temperature proximate the sensing junctions and the temperature proximate the reference junctions arising from chemical reactions facilitated by said substance adjacent said sensing junctions but not adjacent said reference junctions.

A method of measuring the concentration of a chemical within a fluid substantially independently of the absolute temperature of the fluid, the method comprising the steps of:

• a. placing within the fluid a sensor, the sensor including a thin film thermopile disposed upon a supporting substrate and including a plurality of pairs of thin film thermocouple junctions, each of said pairs of thermocouple junctions including a reference junction and a sensing junction electrically coupled in series connection with one another and spaced apart from one another, said reference junction and said sensing junction within each pair of thin film thermocouple junctions each creating a temperature-dependent voltage, each such pair of thermocouple junctions creating an electrical potential proportional in magnitude to the temperature difference between the reference junction and the sensing junction thereof, said plurality of pairs of thermocouple junctions being electrically coupled in series connection with one another between first and second terminals to multiply the electrical potential difference created by each such pair of thin film thermocouple junctions, the sensor including a layer of a substance disposed proximate to each of said sensing junctions but not overlying the reference junctions, said substance facilitating chemical reactions involving said chemical dissolved in said fluid adjacent said sensing junctions but not adjacent said reference junctions;
• b. measuring a voltage difference signal across the first and second terminals of the thin film thermopile to detect the difference between the temperature proximate the sensing junctions and the temperature proximate the reference junction arising from chemical reactions facilitated by said substance adjacent said sensing junction but not adjacent said reference junctions;
• and
• c. deriving from said voltage difference signal an indication of the concentration of said chemical within the fluid.

A method of measuring the concentration of a chemical within the blood of a living body substantially independently of the absolute temperature of the blood, said method comprising the steps of:

• a. contacting the blood of the living body with a sensor, the sensor including a thin film thermopile disposed upon a supporting substrate and including a plurality of pairs of thin film thermocouple junctions, each of said pairs of thermocouple junctions including a reference junction and a sensing junction electrically coupled in series connection with one another and spaced apart from one another, said reference junction and said sensing junction within each pair of thin film thermocouple junctions each creating a temperature-dependent voltage, each such pair of thermocouple junctions creating an electrical potential proportional in magnitude to the temperature difference between the reference junction and the sensing junction thereof, said plurality of pairs of thermocouple junctions being electrically coupled in series connection with one another between first and second terminals to multiply the electrical potential difference created by each such pair of thin film thermocouple junctions, the sensor including a layer of a substance disposed proximate to each of said sensing junctions but not overlying the reference junctions, said substance facilitating chemical reactions involving said chemical dissolved in said blood adjacent said sensing junctions but not adjacent said reference junctions;
• b. measuring a voltage difference signal provided by said wiring means;
• and
• c. deriving from said voltage difference signal an indication of the concentration of said chemical within the blood of the living body.