In-Situ Saw/Baw Sensors Based on P(VDF-TRFE) for Strain and Temperature Measurement

The paper presents an in-situ Surface Acoustic Wave (SAW) / Bulk Acoustic Wave (BAW) sensor based on P(VDF-TrFE), which is directly integrated onto a metal surface. Characterization results confirm that the P(VDF-TrFE) film is well-suited for fabricating SAW/BAW sensors. The sensor excites multiple BAW modes, enabling temperature sensing with a maximum temperature coefficient of frequency (TCF) of 738 ppm/°C in BAW mode 3, which is six times higher than the reported in-situ BAW devices. In SAW mode 1, the TCF reaches 745 ppm/°C, almost eight times greater than the previous in-situ SAW devices. Moreover, the SAW mode 1 exhibits good linearity across a large strain measurement range of 7000 με, with a sensitivity of 146 Hz/με, surpassing the strain range of the reported in-situ SAW devices by nearly fourfold. Overall, the developed in-situ SAW/BAW sensor features outstanding performance in both temperature and strain sensing, which demonstrates the significant potential for multifunctional and multimodal sensing applications in structural health monitoring (SHM).