Apparatus for electrochemical measurements
First Claim
1. A sensor system for measuring the concentration of an electrochemically active species in an electrolyte, comprising a substrate;
- a working electrode supported by said substrate;
a reference electrode supported by said substrate;
a counter electrode supported by said substrate, at least one of said electrodes being formed by thick film or thin film techniques as a layer of electrically conductive material on said substrate;
a layer of electrically insulating material on at least a portion of said layer of electrically conductive material, said layer of electrically insulating material having discontinuities to expose individual plural electrode portions;
electrical means for providing energy to said electrodes, said electrical means including means for applying voltage potentials to said electrodes and feedback means for controlling the voltage between said reference and counter electrodes thereby to maintain a constant voltage across said working and reference electrodes, such that balanced but reverse ionization reactions of such species respectively occur at said workiing and counter electrodes while essentially no reaction occurs at said reference electrode; and
current measuring means for measuring current flow between said working and counter electrodes as a representation of the concentration of such species.
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Abstract
A sensor for an electrochemically active species, such as oxygen, uses more than two electrodes, namely, at least a working electrode, counter electrode and reference electrode. The sensor preferably is substantially planar, is made using thick film or thin film technique and accordingly may be very small. With the sensor in an electrolyte balanced reverse reactions occur, respectively, at the working and counter electrodes while no reaction occurs at the reference electrode, which is maintained in equilibrium with the electrolyte, and voltage between the working the reference electrodes is maintained constant. Current flow between the working and counter electrodes, then, provides an accurate, stable representation of species concentration.
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Citations
32 Claims
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1. A sensor system for measuring the concentration of an electrochemically active species in an electrolyte, comprising a substrate;
- a working electrode supported by said substrate;
a reference electrode supported by said substrate;
a counter electrode supported by said substrate, at least one of said electrodes being formed by thick film or thin film techniques as a layer of electrically conductive material on said substrate;
a layer of electrically insulating material on at least a portion of said layer of electrically conductive material, said layer of electrically insulating material having discontinuities to expose individual plural electrode portions;
electrical means for providing energy to said electrodes, said electrical means including means for applying voltage potentials to said electrodes and feedback means for controlling the voltage between said reference and counter electrodes thereby to maintain a constant voltage across said working and reference electrodes, such that balanced but reverse ionization reactions of such species respectively occur at said workiing and counter electrodes while essentially no reaction occurs at said reference electrode; and
current measuring means for measuring current flow between said working and counter electrodes as a representation of the concentration of such species. - 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)
- a working electrode supported by said substrate;
- 25. A method of making a sensor for use in sensing electrochemically active species in an electrolyte, comprising using a thick film or thin film depositation method to apply at least three electrically isolated electrodes to a substrate consisting of a working electrode, counter electrode and reference electrode, and then forming an electrically insulating layer over at least a part of the working electrode with discrete plural discontinuities to expose plural individual electrode portions thereby to provide for relatively high current density and energy level in proximity to such electrode portions for inducing a desired reduction reaction.
- 30. A sensor for an electrochemically active species, comprising a substrate, a working electrode supported by said substrate, a reference electrode supported by said substrate, a counter electrode supported by said substrate, at least one of said electrodes including a layer of electrically conductive material on said substrate, and a layer of electrically insulating material on at least a portion of said layer of electrically conductive material, said layer of electrically insulating material having discontinuities to expose individual plural electrode portions.
Specification