A micromachined calorimetric gas sensor: an application of electrodeposited nanostructured palladium for the detection of combustible gases

Palladium films with regular nanoarchitectures were electrochemically deposited from the hexagonal (Hi) lyotropic liquid crystalline phase of the nonionic surfactant octaethyleneglycol monohexadecyl ether (C16EO8) onto micromachined silicon hotplate structures. The H-1-e Pd films were shown to have high surface areas (similar to28 m(2) g(-1)) and to act as effective and stable catalysts for the detection of methane in air on heating to 500 degreesC. The response of the H-1-e Pd-coated planar pellistors was found to be linearly proportional to the concentration of methane between 0 and 2.5% in air with a detection limit below 0.125%. Our results show that the electrochemical deposition of nanostructured metal films offers a promising approach to the fabrication of micromachined calorimetric gas sensors for combustible gases.