Synergetic Enhancement of Piezoelectric P(VDF-TrFE) Devices toward Weak Signal Perception

In recent years, flexible piezoelectric polymers and devices have attracted significant attention due to the booming development of artificial intelligence and the internet of Things. Piezoelectric polymers, typically poly(vinylidene fluoride) (PVDF) and its copolymer with trifluoroethylene (P(VDF-TrFE)), offer several distinct advantages such as intrinsic flexibility, ease of processing, chemical inertness, and biocompatibility. However, their relatively lower piezoelectric coefficients compared with their inorganic counterparts greatly limit practical applications in high-performance sensors and energy harvesters. Both modulation of microstructure and construction of three-dimensional (3D) structured devices have been demonstrated to be effective measures to enhance the piezoelectric performance. This work focused on the fabrication of highly sensitive copolymer sensors by coordination of both polytetrafluoroethylene template-induced crystallization and construction of wave-shaped 3D devices. Template-induced crystallized P(VDF-TrFE) devices demonstrated an average d33 coefficient of −40.9 pC/N within a frequency range of 100–1000 Hz. Further construction of wave-shaped 3D piezoelectric devices promoted their sensitivity to weak mechanical excitation. This wave-shaped device detected diversities of physiological and action signals of the human body. With the help of a pulse wave velocity model, wave-shaped devices were utilized for blood pressure measurements along with pulse detection. The device was further extended for audible sound detection with a frequency resolution better than 1 Hz and the capability of frequency spectrum analysis of varieties of acoustic sources. This work provides a convenient and effective strategy to construct high-performance and flexible piezoelectric devices for weak signal detection.