High-Sensitivity Arrayed Stretchable Piezoelectric Force Sensor Based on PVDF-TrFE/Nano-Fe₃O₄ Nanofibers

Flexibility piezoelectric sensors play an extraordinarily significant role in force detection in many fields, such as biomedical, mechanical engineering, environmental monitor and measurement, and others. The limitations of the performance of sensing materials and sensor functionality, however, restrict their applications. Herein, a high-sensitivity arrayed stretchable piezoelectric force sensor based on polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE)/nano-Fe3O4 was proposed. The flexible sensor consists of a double-layer Polydimethylsiloxane (PDMS) substrate with different ratios of main agent and curing agent, serpentine stretchable silver electrodes, and a nanofiber-sensitive layer. The composite nanofiber was fabricated by doping Fe3O4 nanoparticles (NPs) into PVDF-TrFE and using high-voltage electrospinning technology. X-ray diffraction (XRD) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy results indicate that the addition of Fe3O4 NPs promotes the formation of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> phase in the PVDF-TrFE polymer. Comparative experiments demonstrate that when the Fe3O4 NP content is 5 wt%, the sensor exhibits better frequency (higher than 16 V at 3 Hz) and faster response time (45 ms). More importantly, the arrayed stretchable piezoelectric force sensor demonstrates exceptional sensitivity in detecting pressure, stretching, and bending deformations, with values of 740 mV/kPa, 380 mV/N, and 21.16 mV per 10% deformation, respectively. It also exhibits high reliability, as its output maintains durability and stability after undergoing 10 000 stability cycles at 7 Hz. Application experiments with the arrayed sensor reveal its capability to detect distributed forces applied by weights and fingers, presenting novel applications in identifying object weight and hardness. In looking ahead, this research offers an unprecedented multimodal detection strategy for next-generation stretchable sensors, demonstrating exceptional practicality.