Solid state gas sensor design using foreign receptors

Sensory detection of gases has become increasingly important especially for emission control and environmental monitoring. This article reviews how we ll a design concept using foreign receptors works for developing three type s of solid state pas sensors. For oxide-semiconductor gas sensors, noble me tals, metal oxides or even metal carbonates can works as an effective recep tor material to recognize reducing Bases when finely dispersed on the base oxide grains. Alkaline metal salts of oxyacids can work as indispensable re ceptors to oxidic gases like CO2, NO2 and SO2 for potentiometric solid elec trolyte gas sensors, while semiconducting oxides provide useful receptors t o reducing or oxidizing gases when used as a sensing electrode for mixed po tential type solid electrolyte gas sensors. Several gas sensors thus develo ped are demonstrated together with brief discussion.