A Flexible Film Bulk Acoustic Resonator Based on β-Phase Polyvinylidene Fluoride Polymer

Sensors

Zijing Fang¹  Lin Shi¹  Xiang Tao¹  Hao Jin¹  Leihe Lu¹  Jikui Luo¹  Ting Wu¹  Shuyi Huang¹  Shurong Dong¹  Shuting Liu¹  Hongsheng Xu¹  Weipeng Xuan² 

[1] Key Lab. of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China;Ministry of Education Key Laboratory of RF Circuits and Systems, Hangzhou Dianzi University, Hangzhou 310018, China;

关键词: bulk acoustic wave;    β-phase pvdf polymer;    flexible device;    strain sensor;    temperature sensor;   

DOI  :  10.3390/s20051346

来源: DOAJ

【 摘 要 】

This paper reports a novel flexible film bulk acoustic resonator (FBAR) based on $\mathsf{\beta }$ -phase polyvinylidene fluoride (PVDF) piezoelectric polymer. The proposed device was simulated and evaluated; then, a low-temperature photolithography process with a double exposure method was developed to pattern the electrodes for the device, which enabled the device to retain the piezoelectric properties of the $\mathsf{\beta }$ -phase PVDF film. Results showed that the β-phase PVDF FBARs had a resonant frequency round 9.212 $\mathrm{MHz}$ with a high electromechanical coupling coefficient ( $k^2$ ) of 12.76% ± 0.56%. The device performed well over a wide bending-strain range up to 2400 $\mathsf{\mu }\mathsf{\epsilon }$ owing to its excellent flexibility. It showed good stability as a strain sensor with a sensitivity of 80 $\mathrm{Hz}/\mathsf{\mu }\mathsf{\epsilon }$ , and no visible deterioration was observed after cyclic bending tests. The PVDF FBAR also exhibited an exceptionally large temperature coefficient of frequency (TCF) of −4630 $\mathrm{ppm}/\mathrm{K}$ , two orders of magnitude larger than those of other FBARs based on common inorganic piezoelectric materials, extraordinarily high sensitivity for temperature sensing. All results showed that $\mathsf{\beta }$ -phase PVDF FBARs have the potential to expand the application scope for future flexible electronics.

【 授权许可】

Unknown