APPLICATION OF PLASMA-POLYMER-FILM-COATED SENSORS TO GAS IDENTIFICATION USING LINEAR FILTERS

A chemical sensing system that uses a new type of sensor film and digi tal signal processing of sensor dynamic responses is described. It con sists of quartz-crystal microbalances coated with plasma-polymer films . The sensor dynamic responses include information about the target ga ses, and are described by linear filters the coefficients of which ref lect the sensor's dynamics and which can extract the dynamic parameter s, even when the gas concentrations change, using multiple sensors wit h different dynamic characteristics. This method is applicable to vari ous uses under practical conditions. The application of the proposed m ethod to a fire-alarm system is described. This system can discriminat e between the gases from burning polyvinyl chloride (PVC) cables and c ircuit boards. Finally, some simulation results indicate that it is si gnificant for these sensors to have different dynamic properties when the sensors' outputs are greatly disturbed by noise.