Electrochemical sensors made from conductive polymer composite materials and methods of making same
First Claim
1. A reversible electrochemical sensor for detecting the presence of chemical analytes comprising:
- (a) a conductive polymer composite of an immiscible polymer blend, said blend comprising (1) a conductive filler material, (2) a minor phase material in which said conductive filler material is dispersed in an amount sufficient to generate a continuous conductive network in said minor phase material and forming a binary composite, and (3) a major phase material with an affinity for at least one analyte, said major phase material being a polymer which when mixed with said binary composite will not engage in electrostatic interactions that promote miscibility, said major phase material having said binary composite dispersed therein in an amount sufficient to generate a continuous conductive network in said major phase material and forming a conducive ternary composite having distinct co-continuous phases; and
(b) a pair of electrodes in electrical contact with said conductive ternary composite, wherein electrical properties of said conductive ternary composite undergo a reversible change when in proximity to at least one analyte.
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Abstract
An electrochemical sensor which is tailored for sensitivity to specific chemical analytes by selecting proper constituents. The electrochemical sensor is comprised of an immiscible polymer blend of at least two polymers in which a conductive filler is dispersed in one of the polymers of the blend through a multiple percolation approach to compounding. When in the presence of a chemical analyte which is in either a liquid or vapor phase, one phase of the dual immiscible polymer blend swells, effecting a decrease in the conductivity, or increase in resistivity, of the polymer blend. The electrochemical sensor is reversible in that when the chemical analyte evaporates or is removed, the polymer blend returns to its original conductivity. With the multiple percolation approach it is possible to make a single composite material identifiably sensitive to various chemical analytes by incorporating several major phase materials into the immiscible polymer blend, each having an affinity for swelling for a different analyte. Further, the multiple percolation approach allows sensors to be made at extremely low cost.
78 Citations
35 Claims
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1. A reversible electrochemical sensor for detecting the presence of chemical analytes comprising:
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(a) a conductive polymer composite of an immiscible polymer blend, said blend comprising (1) a conductive filler material, (2) a minor phase material in which said conductive filler material is dispersed in an amount sufficient to generate a continuous conductive network in said minor phase material and forming a binary composite, and (3) a major phase material with an affinity for at least one analyte, said major phase material being a polymer which when mixed with said binary composite will not engage in electrostatic interactions that promote miscibility, said major phase material having said binary composite dispersed therein in an amount sufficient to generate a continuous conductive network in said major phase material and forming a conducive ternary composite having distinct co-continuous phases; and
(b) a pair of electrodes in electrical contact with said conductive ternary composite, wherein electrical properties of said conductive ternary composite undergo a reversible change when in proximity to at least one analyte. - 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 second major phase material, said second major phase material having an affinity for a second analyte, wherein said conductive ternary composite is dispersed in an amount sufficient to generate a continuous conductive network in said second major phase material, said second major phase material being selected from that group of polymers which when mixed with said conductive ternary composite will not engage in electrostatic interactions that promote miscibility with said minor phase material or with said major phase material, forming a conductive quaternary composite having distinct co-continuous phases, wherein electrical properties of said conductive quaternary composite undergo a reversible change when in proximity to said second analyte.
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20. The electrochemical sensor of claim 19 wherein the electrical properties of said conductive quaternary composite are selected from the group comprising resistance, conductance, and capacitance.
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21. The electrochemical sensor of claim 19, further comprising means for crosslinking said conductive quaternary composite.
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22. The electrochemical sensor of claim 19, further comprising one or more additional major phase materials, each of said additional major phase materials being polymers having an affinity for additional analytes, said additional major phase materials being polymers which when mixed with each other, with said major phase material, with said second major phase material, and with said minor phase material will not engage in electrostatic interactions that promote miscibility, forming a conducting multi-phase composite having distinct co-continuous phases, wherein the conductivity of said conducting multi-phase composite undergoes a reversible change when in proximity to one of said additional analytes.
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23. The electrochemical sensor of claim 22, further comprising means for crosslinking said conducting multi-phase composite.
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24. The electrochemical sensor of claim 1, wherein said conductive polymer composite further comprises a material selected from the group consisting of antioxidants, nucleating agents, coupling agents, ultraviolet absorbers, ultraviolet stabilizers, pigments, dyes, reinforcing fillers, slip agents, plasticizers, processing aids, lubricants, viscosity control agents, tackifiers, anti-blocking agents, surfactants, extender oils, metal deactivators, voltage stabilizers, flame retardant fillers, cross-linking agents, boosters, catalysts, smoke suppressants, and combinations thereof in the amount of about 0.05% by weight to about 50% by weight of said conductive polymer composite.
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25. A method of producing a reversible electrochemical sensor for detecting the presence of chemical analytes comprising:
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mixing a minor phase polymer having a melting temperature at a temperature greater than or equal to said melting temperature of said minor phase polymer;
mixing a conductive filler with said minor phase polymer in an amount greater than or equal to an amount required to generate a continuous conductive network in said minor phase polymer for a time and at a sufficient speed to insure a uniform distribution of said conductive filler in said minor phase polymer, thereby forming a binary composite having a melting temperature;
mixing a major phase material having a melting temperature with said binary composite in a mixer preheated to at least the melting temperature of said major phase material and the melting temperature of said binary composite, for a time and at a sufficient speed to insure a uniform distribution of said binary composite in said major phase material, such that a weight ratio of said binary composite to said major phase material is sufficient for said binary composite to be equal to or greater than an amount required to generate a continuous conductive network in said major phase material, said major phase material being selected from that group of polymers which when mixed with said binary composite will not engage in electrostatic interactions which promote miscibility, such that a conductive ternary composite with co-continuous phases is formed; and
securing a pair of electrodes to said conductive ternary composite, said pair of electrodes being in electrical contact with said conductive ternary composite. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification