Ultra-sensitive flexible piezoelectric energy harvesters inspired by pine branches for detection

Realization of self-powered sensing devices has received substantial attention employing flexible piezoelectric energy harvesters (PEH). For effective implement, robust sensing and response capability to external mechanical load are demanded for PEH, which has been challenging. Here, flexible and ultra-sensitive PEH filled with pine-branch-inspired three-dimensional TiO2@polydopamine@Ag (3D TPA) fillers are proposed. Benefitting from the bioinspired structure design, the PEH device with incredible piezoelectric characteristics combining measurable output voltage and power density (similar to 100 V and similar to 184.06 mu W cm(-2)) contributes to reliable power source supply for sustainably drive electronic devices. Notably, the PEH device could be considered as piezoelectric sensors with ultra-sensitive sensing performances comprising high sensitivity (46.2 V N-1 and 6.64 mu A N-1), low detection threshold (10 mg) and fast response time (1 ms) for detecting dropped tiny objects. The extraordinary piezoelectric outputs enhancement is put down to the multiple coupling induced by the 3D TPA, including improvement of load-transfer efficiency and poling electric field, which has been confirmed by experiment results and theoretical simulations. This work opens a novel insight to access 3D fillers and has a profound influence on the rational preparation of ultra-sensitive PEH for potential application in smart piezoelectric sensors.