Impedance studies of chemiresistive platforms used in gas sensors

摘要

The presented work describes experimental results obtained from impedance studies on chemiresistive platforms used to detect vapors of 18 solvent vapors. The goal was to ascertain viability of impedance spectrum measurement over a simple resistance measurement with DC current. In some cases the AC approach had justifiable advantage over DC. In order to use the AC spectroscopy measurement, the platform must be from a substrate that is nonconductive in its bulk. Other issues studied were the effect of magnitude of applied AC signal and a comparison of the 2-point and the 4-point connection of the impedance bridge. The 4-point connection may be advantageous in some cases. For systems with thin, highly resistive films, and for systems with polyaniline conductive material the impedance spectroscopy, or AC measurement at several frequencies had better response than that obtained from a DC current measurement.