Response of a poly(pyrrole) resistive micro-bridge to ethanol vapour

In this paper the authors describe the behaviour of a silicon micro-bridge fabricated with four conducting polymer resistive elements (two active) in a CMOS-compatible process. The poly(pyrrole) (PPy) bridges were characterised using a precision analogue interface circuit with the constant-current drive and voltage off-set set by a Labview Virtual Instrument. The responses of eight polymer micro-bridges to ethanol vapour were recorded at different temperatures and humidity's. The output voltage of the bridge circuit followed the classical Langmuir adsorption isotherm in concentration and generally fell with increasing temperature and humidity. A typical bridge sensitivity to ethanol of ca. 30 mu V/ppm was observed at room temperature with the linear temperature coefficient of the operation being relatively high at - 2.8 x 10(-2)/degrees C. (C) 1998 Elsevier Science S.A. All rights reserved.