Development of wireless, batteryfree gyroscope based on one-port SAW delay line and double resonant antenna

A wireless, battery-free micro-gyroscope was developed by employing a one-port surface acoustic wave (SAW) reflective delay line, a SAW resonator, and an antenna. Two SAW devices with different center frequencies were simultaneously activated by a single antenna with double resonant frequencies. An 80 MHz RF energy from antenna activates a double-port SAW resonator while a 195 MHz RF energy activates a one-port SAW delay line. The fabricated gyroscope showed clear reflection peaks with high signal-to-noise (S/N) ratios in both the time and frequency domains in measurement system during wireless testing. Upon rotation of the device, large shifts of the reflection peaks were observed owing to a secondary wave interference effect caused by the Coriolis force that depends on the spinning rate. The measured sensitivity and linearity of the developed gyroscope were, respectively, 1.35 deg/(deg/s) and 0.91, which are promising values for our targeted applications. The temperature, metal mass effect, and vibration/shock effects were also studied and the results are discussed.