Flexible Strain Sensor Based on Ultra-Thin Quartz Plate

In the past few years, many types of surface acoustic wave (SAW) strain sensors have been developed using various piezoelectric substrates to improve detectable range and sensitivity. In this paper, we report a SAW flexible strain sensor based on ultra-thin AT-X quartz plate with a thickness of 31
$\mu {\mathrm {m}}$
. The sensor has a high sensitivity of
$251.9 \mathrm{~Hz} / \mu \varepsilon$
, an excellent linearity for the strain range from 1 to
$5000~\mu \varepsilon$
, and which is about 12 times higher than those of other SAW strain sensors based on bulk substrates. The resolution of the sensors is about 3280 Hz in frequency and
$14~\mu \varepsilon$
in strain. Moreover, the sensors exhibit a very low temperature coefficient of frequency (TCF) of about −1.06 ppm/°C in the temperature range from 20 to 80°C. Our new sensor paves the way for the fabrication of high-performance strain sensing devices.