AN AUTOMATED SAW GAS SENSOR TESTING SYSTEM

An automated, reliable and safe system for the unattended and safe tes ting of surface acoustic wave (SAW) gas sensors has been developed. Th e system includes the possibility of generating and/or diluting almost any gas or vapour and can easily be adapted for testing sensors or eq uipment other than SAW sensors. A large range of concentrations is ach ievable by the option of single-stage or two-stage dilution. The relia bility of the gas-generation system is guaranteed by the continuous mo nitoring of the concentration and the relative humidity of the gas gen erated as well as the temperature of the measuring cell. Aspecific sam pling effects on the sensor response are excluded by using the same co nditions (temperature, humidity and flow rate) for the diluting and th e reference gas flows. Examples are given of recent research on SAW ga s sensors employing the system, i.e., the development of a silicon-bas ed SAW sensor for NO2 and a SAW gas sensor for organophosphorus chemic al warfare agents.