Yujie Wu,Chun-Yan Tang,Shan Wang,Jiaxing Guo,Qi Jing,Junhong Liu,Kai Ke,Yu Wang,Wei Yang
Flexible piezoelectric pressure sensors have aroused a plethora of applications in wearable electronics, acoustic transducers, and energy harvesters thanks to many merits such as prompt response, good signal linearity, and ease of shaping. However, as all-polymer piezoelectric films have a low piezoelectric coefficient and severe stress dissipation, it is currently challenging to achieve a high piezoelectric output for the foregoing applications without introducing nanomaterials or piezoelectric ceramics. Here, we report a local stress engineering strategy to fabricate biomimetic all-fluoropolymer piezoelectric film pressure sensors with high-modulus poly(vinylidene fluoride) (PVDF) nanospheres embedded on low-modulus poly(vinylidene fluoride-trifluoride ethylene) (PVDF-TrFE) nanofibers for highly sensitive acoustic detection. High-modulus PVDF nanospheres create many local stress concentration sites on PVDF-TrFE nanofibers and increase the local deformation, leading to significantly improved force/pressure sensitivity. As such, by comparison with the force sensitivity of 60 mV/N for neat PVDF-TrFE, the heteromodulus fiber mats with 10 wt % PVDF nanospheres can achieve a force sensitivity of 145.1 mV/N over 0–25 N dynamic impact force (i.e., 0 ∼ 250 kPa pressure), together with an acoustic detection limit as low as 60 dB or 0.02 Pa.
Flexible pressure sensors hold great potential for electronic skins and wearable devices. However, conventional piezoresistive flexible pressure sensors often lack the ability to detect high-frequency dynamic stimuli. Here we present a piezoresistive flexible pressure sensor by combining porous materials with a pyramid array composite hierarchical structure. The sensor significantly improve the response-relaxation time and can accurately capture dynamic stimuli exceeding 20 kHz with a frequency resolution of 0.1 Hz. Meanwhile, the sensor can detect a minimum pressure of 1 Pa and has a wide pressure sensing range from 1 Pa to 1000 kPa. In addition, we developed a structural vibration detection system, a sound detection system, and a human motion detection system to verify the broadband multifunctional detection capability of the sensor. This work provides innovative ideas for the development of flexible wearable devices and electronic skins.
危险品化学品经营许可证（带存储）