Electret and rhodium gas sensors

The organic gas-sensing characteristics of an electret and a rhodium probe are presented and discussed. The electret consists of a negatively charged PFA polymer layer bonded to a metal back. The electret detects changes in organic gas concentration as a result of dipole-charge and induced dipole-charge interactions between the adsorbed gas and negative charge in the PFA polymer layer. The rhodium-plated probe senses changes in organic gas concentration due to electron donor/acceptor interactions between the adsorbed gas and surface of the probe. The rhodium probe is able to distinguish between strong and weak electron donor gases by the polarity of the response signal.