A VERSATILE SAW-BASED SENSOR SYSTEM FOR INVESTIGATING GAS-SENSITIVE COATINGS

Surface acoustic wave (SAW) technology is an extremely versatile techn ique for the development of gas sensors because of the SAW device's se nsitivity to a wide variety of material properties that can change wit h gas concentration. In the present work, a SAW sensor oscillator is d escribed, which allows both of the important SAW properties, velocity and attenuation, to be easily measured. The SAW sensor can be used wit h a variety of gas-sensing materials to monitor any gases that interac t with the sensing materials. The versatility of the sensor is demonst rated by making SAW sensors using two gas-sensitive films that work in different ways. A tungsten trioxide (WO3) film with electrical proper ties that vary with hydrogen sulfide (H2S) exposure has been used to m ake a SAW H2S sensor, and an organic material that sorbs solvents has been used to demonstrate a SAW acetone sensor.