AN AUTOMATED SAW GAS SENSOR TESTING SYSTEM

An automated, reliable and safe system for the unattended and safe testing of surface acoustic wave (SAW) gas sensors has been developed. The system includes the possibility of generating and/or diluting almost any gas or vapour and can easily be adapted for testing sensors or equipment other than SAW sensors. A large range of concentrations is achievable by the option of single-stage or two-stage dilution. The reliability of the gas-generation system is guaranteed by the continuous monitoring of the concentration and the relative humidity of the gas generated as well as the temperature of the measuring cell. Aspecific sampling effects on the sensor response are excluded by using the same conditions (temperature, humidity and flow rate) for the diluting and the reference gas flows. Examples are given of recent research on SAW gas sensors employing the system, i.e., the development of a silicon-based SAW sensor for NO2 and a SAW gas sensor for organophosphorus chemical warfare agents.