A high-performance surface acoustic wave sensing technique.

We present a superheterodyne-scheme demodulation system that can detect the amplitude and phase shift 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 <0.1 ppm velocity shift. Furthermore, we investigate the possibility of using this surface acoustic wave device as a calibration-free, high sensitivity, and fast response thermometer.