Resettable, low-temperature accumulation gas sensors based on hydrogenated diamond transducers

Diamonds with hydrogenated surfaces feature a gas sensitivity which is mediated by a thin layer of BET-adsorbed water (BET: Brunauer, Emmet, Teller). Gases capable of undergoing acid-base reactions in liquid water are absorbed in the BET adsorbate, producing pH changes there and easily observable changes in the sub-surface hole conductivity of the diamond substrates. In this contribution we report on vapor sensing tests with diamond sensors which have been performed at normal ambient temperatures in a free-space environment. We show that such sensors exhibit an integrating dosimeter type response, which follows the temporal vapor concentrations with a time resolution of the order of one second or less. Upon saturation the sensors can be repeatedly reset to baseline by replacing contaminated BET adsorbates by fresh-water ones.