Gas sensor and method of using same
First Claim
1. A system for determining the concentration of carbon dioxide in a subject fluid comprising a sensor comprising at least a working electrode which will reductively adsorb carbon dioxide, a counter electrode, and means whereby said subject fluid containing carbon dioxide contacts said working electrode, said electrodes of said sensor being connected to a current or potential controlling device which, in turn, is connected to a current integrator, whereby carbon dioxide reductively adsorbed on said working electrode of said sensor is measured.
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Accused Products
Abstract
An electrochemical sensor capable of determining the partial pressure of various gases (e.g., CO, CO2, H2 S, alcohol vapors, hydrocarbons, NOx, etc.) and, optionally, substantially concurrently, but independently, oxygen content in gases and liquids. The sensor measures the amount of chemisorbent species formed either electrochemically by partial reduction (such as "Reduced-CO2 " in the case of CO2) or partial oxidation (in the case of alcohol) or non-electrochemically via specific adsorption (in the case of CO and hydrocarbons) on platinum or other metals. The charge required to oxidize this chemisorbed species is proportional to the amount of adsorbate on the electrode surface which is made a reproducible and reliable function of the partial pressure of the gas to be measured. By the proper selection of the sensor construction and electrical parameters, high sensitivity, fast response time, and high selectivity can be obtained.
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Citations
22 Claims
- 1. A system for determining the concentration of carbon dioxide in a subject fluid comprising a sensor comprising at least a working electrode which will reductively adsorb carbon dioxide, a counter electrode, and means whereby said subject fluid containing carbon dioxide contacts said working electrode, said electrodes of said sensor being connected to a current or potential controlling device which, in turn, is connected to a current integrator, whereby carbon dioxide reductively adsorbed on said working electrode of said sensor is measured.
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6. Apparatus for sensing and measuring a gas comprising:
- 7. (1) at least a working electrode, a counter electrode, a reference electrode, and an electrolyte inside of an enclosure and in contact with an external medium by means of a hydrophobic membrance;
- 8. (2) means to regulate the potential of the working electrode so as to produce repeatable temporal function of potential with a total period of less then five minutes, said function containing at least a potential region for formations of a gas-derived adsorbate and a potential region for measurement of the adsorbed species;
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9. (3) means to measure amount of adsorbate.
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10. A gas sensor for determining the concentration of gases in a subject fluid comprising at least a working electrode which will adsorb a gas, a counter electrode, an electrolyte in contact with each of said electrodes, a support structure, and a hydrophobic membrane;
- said support structure and hydrophobid membrane forming an enclosure within which said electrolyte is contained and separated from said subject fluid;
said hydrophobic membrane being constructed and arranged to permit passage of gases from said subject fluid to said electrolyte for contact with said working electrode; and
means for controlling the electrical potential or current of said working electrode including electrical means to form on said working electrode chemisorbed species originating from said gases, and electrical means to measure the amount of said chemisorbed species.
- said support structure and hydrophobid membrane forming an enclosure within which said electrolyte is contained and separated from said subject fluid;
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22. A gas sensor for determining the concentration of gases in a subject fluid comprising at least a working electrode which will adsorb a gas, a counter electrode, an electrolyte in contact with each of said electrodes;
- and means for controlling the electrical potential or current of said working electrode including electrical means to form on said working electrode chemisorbed species originating from said gases, and electrical means to measure said chemisorbed species.
Specification