Experiments for self-temperaturecompensated characteristics of SAW gas sensor at fundamental and third-harmonic frequencies

A novel surface acoustic wave (SAW) gas sensor with self-temperature- compensated characteristics is proposed. Any type of piezoelectric crystal substrate irrelevant to their temperature coefficients of SAW velocities, can be adopted in this gas sensor. The sensing dynamic range can be extended utilising both the fundamental and third-harmonic frequency signals. Experimental results at the 75 MHz fundamental frequency and the 225 MHz third-harmonic frequency showed validity of the proposed sensor structure.