Flexible, stable and durable polydopamine@lead zirconate titanate/polyimide composite membranes for piezoelectric pressure sensors and limb motion monitoring

Flexible piezoelectric pressure sensors have been paid great attention in wearable electronic devices, obtaining mechanical energy and driving portable devices. Presently, membranes based on piezoelectric ceramic/polymer composite materials encounter problems such as filler agglomeration and surface defects, which affects the energy conversion performance of piezoelectric devices. Herein, the surface of lead zirconate titanate (Pb(Zr0.52Ti0.48)O3, PZT),was modified by coupling agent-polydopamine (Pdop), and combined with the polyimide (PI) matrix by in-situ polymerization to form a uniform Pdop@PZT/PI composite. This polydopamine modification method increases the compatibility between the two components, and promotes the dispersion of PZT in the polyimide matrix more uniform. Under the external force of 10 N, the maximum open circuit voltage of Pdop@PZT/PI-based piezoelectric pressure sensor (PPS) can reach 12.8 V. In addition, the sensitivity of the sensor is 1.4 V/N (0.24 V/kPa), which can maintain a stable output voltage under different frequencies of external force. After 10,000 cycles of periodic impacting/releasing, the open circuit voltage of PPS remained stable, indicating that the device has excellent stability and durability. It has the potential to be used as self-powered wearable sensors and detect human motion in daily life.