A Wearable and Highly Sensitive PVDF–TrFE–BaTiO₃ Piezoelectric Sensor for Wireless Monitoring of Arterial Signal

As wearable electronics advance, there is a growing need for flexible sensors with high sensitivity to detect even the slightest mechanical stimuli for real-time monitoring across various applications. This study presents a poly-(vinylidene fluoride-<i>co</i>-trifluoroethylene) (PVDF-TrFE)-based flexible piezoelectric sensor, developed by electrospinning a composite of PVDF-TrFE and barium titanate (BaTiO₃). The PVDF-TrFE with 3 wt % BaTiO₃, referred to as PVDF-TrFE (3 wt % BTO), exhibits higher crystallinity, increased β-phase content, and enhanced piezoelectric response, achieving a pressure sensitivity of 0.37 V/kPa within a pressure range of 6.4-16 kPa at a fixed frequency of 7 Hz. The flexible sensor developed is also characterized by its ability to detect lower pressure ranges with a linear pressure sensitivity of 0.18 V/kPa over a range of 6.4-22.4 kPa at a fixed frequency of 2 Hz. It also exhibits a frequency sensitivity of 0.7 V/Hz within a frequency range of 2-5 Hz at a constant pressure of 6.4 kPa. The fabricated sensors were integrated with a microcontroller and wireless data transfer system to form a wearable sensor patch that detects biomechanical signals such as wrist bending and radial artery pulse signals, ensuring reliable monitoring of biomechanical signals. Furthermore, spatially sensitive detection was achieved by creating a 3 × 3 pressure array sensor to pinpoint pressure locations. With the wireless data transfer system, sensor signals can be sent to a smartphone, which acts as a pressure locator to track external force positions. This work demonstrates that the pressure sensing device developed using the PVDF-TrFE (3 wt % BTO) sensor has significant and promising potential for real-time physiological detection and wearable healthcare monitoring.