Due to the threat of terrorism and environmental pollution there is great demand for chemical sensors with high sensitivity and good stability towards organophosphorous compounds for real-time monitoring. Among currently available chemical sensors, surface acoustic wave (SAW) devices are very promising for chemical sensing applications due to their small size, low cost, high sensitivity, and reliability

HE Shitang, WANG Wen, LI Shunzhou, and LIU Minghua of Institute of Acoustics, Chinese Academy of Sciences described advances in SAW chemical sensors relating to the response mechanism, design and fabrication of the SAW oscillator.

They pointed out that the response mechanism of the PECH-coated SAW chemical sensor extracts the optimal design parameters. New phase modulation methods and new design of the SAW device result a great improvement of the frequency stability of the SAW oscillator, with a measured result of up to ±2.5 Hz in seconds for the 300 MHz oscillator. Then, using the PECH as the sensor material for HD detection, the fabricated SAW chemical sensor with 300 MHz was characterized in gas adsorption. Superior performance like high sensitivity (25 Hz/mg/m3 superior linearity, and good stability were obtained experimentally.

This research result was published recently on 16th International Conferences on Solid-State Sensors, Actuators and Microsystems (2011, pp:1144-1147)