Progress in Semiconductor Gas Sensor Design

摘要

Semiconductor gas sensors of a resistive type utilize porous polycrystalline resistors made of semiconducting oxides. The working principle consists of the receptor function played by the surface of each oxide grain and the transducer function played by each grain boundary, but the utility factor of the sensing body also takes part in determining the gas sensitivity. Sensor design concepts are figured out by considering how to enhance each of these key factors. Selection of a base oxide with high mobility of conduction electrons and stability (transducer function), selection of a foreign receptor which enhances surface reactions or adsorption of target gas (receptor function), and fabrication of a highly-porous, thin sensing body (utility factor) are pointed out to be important guidelines of gas sensor design.