A high-performance surface acoustic wave sensing technique

We present a superheterodyne-scheme demodulation system which can detect the amplitude and phaseshift of weak radio-frequency signals with extraordinarily high stability and resolution. As a demonstration, we introduce a process to measure the velocity of the surface acoustic wave using a delay-line device from 30 K to room temperature, which can resolve $\textless$ 0.1ppm velocity shift. Furthermore, we investigate the possibility of using this surface acoustic wave device as a calibration-free, high sensitivity and fast response thermometer.