Highly Sensitive Flexible Pressure Sensor Based on PVDF-TrFE-BaTiO3 Piezoelectric Nanofibers

With the rapid advancement of wearable electronics, there is continuing demand to explore flexible sensors with high sensitivity to detect even the subtlest of mechanical stimuli enabling accurate and real-time monitoring for various applications. Among piezoelectric organic materials, poly(vinylidene fluoride-co-trifluoroethylene) <bold>(</bold>PVDF-TrFE) stands out as a good candidate for the fabrication of flexible and wearable devices with stability and biocompatibility. This letter presents the development and characterization of PVDF-TrFE barium titanate (BaTiO3) (PVDF-TrFE-BaTiO3) composite nanofibers fabricated by electrospinning, demonstrating that the addition of piezoelectric inorganic material BaTiO3 enhances the crystallinity, amount of the beta-phase, and the piezoelectric response. A conformal PVDF-TrFE-BaTiO3 nanofiber-based piezoelectric sensor was further developed and tested under low pressure/vibration for potential wearable applications. The sensor exhibits an enhanced pressure sensitivity of 0.21 V/kPa at a pressure range from 6.4 to 16 kPa at a fixed frequency of 7 Hz, and a frequency sensitivity of 1.72 V/Hz within a frequency range from 2 to 5 Hz at a fixed pressure of 6.4 kPa. This means that the PVDF-BaTiO3-based flexible sensor is particularly sensitive to low-regime mechanical movement holding great potential application in human motion monitoring and wearable devices, such as heartbeat, pulse, and respiration monitoring, for sports performance tracking and healthcare.