Chemically responsive microelectrochemical devices based on platinized poly(3-methylthiophene): variation in conductivity with variation in hydrogen, oxygen, or pH in aqueous solution

Abstract : In this paper we wish to show that metal impregnated conducting polymers can be useful as the active material in microelectrochemical devices that respond to certain chemical changes in aqueous solution. We report here the impregnation of poly(3-methylthiophene) with metallic Pt in order to make the conducting polymer responsive to oxidizing and reducing species, O2 and H2, respectively, in a reversible and reproducible manner at room temperature in aqueous solution. As recently described, poly(3-methylthiophene)-based transistors can be used in aqueous solution to reproducibly respond to a redox signal, e.g. 10 to the -16 power moles of IrC16(2-) can be detected. In principle, any oxidant capable of oxidizing poly(3-methylthiophene) can be detected. However, only those redox reagents capable of equilibrating with the poly(3-methylthiophene) can be useful in turning the transistor on or off. Since the poly(3-methylthiophene)-based transistor has impressive durability to aqueous solutions, rapid response, and excellent transconductance, this chemically sensitive device is an ideal candidate for microsensor development, provided that it can be made responsive to reagents of interest. Impregnation of the polymer with a noble metal capable of equilibrating with aqueous O2 and H2 is our first step in device modification that yields potentially useful functions for the device.