High-performance piezoelectric energy harvesting of vertically aligned Pb(Zr,Ti)O3 nanorod arrays.

Recent developments of self-powered devices and systems have attracted much attention. Lead zirconate titanate (PZT) has been regarded as one of the most promising materials for building high-performance nanogenerators. Herein, vertically aligned PZT nanorod arrays were synthesized on a pre-oxidized Ti substrate in the presence of a surfactant by a one-step hydrothermal method. The PZT nanorod arrays consist of an initial layer of a PZT film and well aligned nanorods with (001)-orientated tetragonal single crystalline structures. The PZT nanorods exhibited a high piezoelectric response with a d 33 value of up to 1600 pm V-1. A piezoelectric energy harvester was fabricated based on the PZT nanorod arrays, which exhibited outstanding energy harvesting performance with an open-circuit output voltage of 3.3 V and 8 V when the devices were pressed by a compressive 10 N force and a finger tapping motion, respectively. Moreover, the average power density generated by those two mechanical stimulations were up to 3.16 and 5.92 µW cm-2 with the external load of 1 MΩ.

Self-Powered Viscosity and Pressure Sensing in Microfluidic Systems Based on the Piezoelectric Energy Harvesting of Flowing Droplets.

The rapid development of microscaled piezoelectric energy harvesters has provided a simple and highly efficient way for building self-powered sensor systems through harvesting the mechanical energy from the ambient environment. In this work, a self-powered microfluidic sensor that can harvest the mechanical energy of the fluid and simultaneously monitor their characteristics was fabricated by integrating the flexible piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers with the well-designed microfluidic chips. Those devices could generate open-circuit high output voltage up to 1.8 V when a droplet of water is flowing past the suspended PVDF nanofibers and result in their periodical deformations. The impulsive output voltage signal allowed them to be utilized for droplets or bubbles counting in the microfluidic systems. Furthermore, the devices also exhibited self-powered sensing behavior due to the decreased voltage amplitude with increasing input pressure and liquid viscosity. The drop of output voltage could be attributed to the variation of flow condition and velocity of the droplets, leading to the reduced deformation of the piezoelectric PVDF layer and the decrease of the generated piezoelectric potential.