Self-Powered Wearable Piezoelectric Sensors Based on Polymer Nanofiber–Metal–Organic Framework Nanoparticle Composites for Arterial Pulse Monitoring

High-performance wearable electronic devices with the capability of converting mechanical force into electrical energy have been gaining increasing attention for biomedical monitoring applications. We present a novel wearable piezoelectric sensor based on a poly(vinylidene fluoride) (PVDF) nanofibrous membrane containing microporous zirconium-based metal–organic frameworks (MOFs) for arterial pulse monitoring. It is shown that the incorporation of 5 wt % of MOF greatly enhances the piezoelectric constant of the polymer fibrous mat by 3.4-fold without significant loss in its flexibility. The nanofibrous composite exhibits a peak-to-peak voltage of 600 mV under an applied force of 5 N, which is superior to many flexible pressure sensors. It is demonstrated that the enhanced piezoelectric performance of the nanofibrous composite is not only attributed to the increased degree of crystallinity and polar β phase content (75%) but also to the surface chemistry and topography of the nanofibers. Evaluations of the piezoelectric output of the sensor attached to the radial artery at normal body conditions reveal significantly better output voltage (568 ± 76 mV) and sensitivity (0.118 V/N) than nanofibrous PVDF devices for wrist pulse monitoring. The results of this work pave a new way to develop flexible piezoelectric nanofibrous sensors based on MOFs for environmentally sustainable energy generation and wearable healthcare monitoring systems.