Chemically Responsive Microelectrochemical Devices Based on Platinized Poly) 3-Methylthiophene): Variation in Conductivity with Variation in Hydrogen, Oxygen, or pH in Aqueous Solution.
Abstract
Microelectrochemical transistors can be prepared by connecting two closely spaced (approximately 1.2 micron) Au microelectrodes (0.1 micron thick x 2.4 micron wide x 50 micron long) with anodically grown poly(3-methylthiphene). The amount of poly(3-methylthiophene) used involves about .0000001 to .000001 moles of monomer per sq cm. The poly(3-methylthiopene) can be platinized by electrochemical reduction of PtC14(2-) at the pair of coated electrodes. The change in conductivity of the poly(3-methylthiophene) with change in redox potential is the basis for amplification of electrical or chemical signals; the conductivity varies by 5 to 6 orders of magnitude upon change in potential from +0.2 (insulating) to +0.7 (conducting) V vs. SCE in aqueous electrolyte. The Pt equilibrates the poly(3-methylthiophene) with the O2/H2O or H2O/H2 redox couples. (Poly(3-methylthiophene)/Pt)-based transistors are shown to be viable room temperature sensors for O2 and H2 in aqueous solution. O2 reproducibly turns on the device. H2 reproducibly turns off the device. A platinized microelectrode of a dimension similar to the microelectrochemical transistor shows only 1.0 nA reduction current upon exposure to 1 atm O2; the current amplification of the transistor is thus a factor greater than 100,000.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 22, 1986
- Accession Number
- ADA171194
Entities
People
- J. W. Thackeray
- M. S. Wrighton
Organizations
- Massachusetts Institute of Technology