Multiferroic BiFeO3-based hydrophobic polymer composites for polarization rationalization-induced piezo-tribo hybrid energy harvesting and versatile self-powered mechanosensing

BiFeO3-poly(vinylidene fluoride) (BFO-PVDF) and BiFO3-polydimethylsiloxane (BFO-PDMS) piezoelectric composite films have been fabricated herein and used to develop flexible piezoelectric-triboelectric hybrid nanogenerators by forming different combinations with aluminium (Al) electrodes (PVDF-Al, PDMS-Al and PDMS-PVDF) using the contact-separation mode. The dielectric permittivity of both the PVDF- and PDMS-based composites has been found to increase from similar to 9 and 3.2 for a filler loading of 3 wt% to similar to 16.6 and 4.7, respectively, for 10 wt% BFO concentration within their matrix. The mechanical stimulus-driven output voltage has also been found to be increased from similar to 7.5 V and 35 V to similar to 18 V and 100 V for the respective films. The rational augmentation of the polarization of PVDF and PDMS induced by the gradually increased BFO filler concentration in their matrix, as confirmed from the above-mentioned results, have been found to significantly affect the output performance of the fabricated piezo-tribo hybrid nanogenerators. Among the three types of fabricated hybrid devices, the combination of 10 wt% BFO-incorporated PDMS with an aluminium electrode shows the best output performance both theoretically and experimentally. Hence, this combination has been used to develop a flexible multi-unit hybrid nanogenerator (M-HNG), which shows further performance enhancement (output power density: similar to 600 mu W cm(-2)). The M-HNG was then used for biomechanical energy harvesting, powering small electronics and different self-powered mechanosensing applications including motion sensing, pressure sensing, water drop counting and phonation monitoring.

Automated summary

BiFeO3-poly(vinylidene fluoride) (BFO-PVDF) and BiFO3-polydimethylsiloxane (BFO-PDMS) piezoelectric composite films were used to develop flexible piezoelectric-triboelectric hybrid nanogenerators. Increasing BFO filler concentration enhanced polarization of PVDF and PDMS, leading to improved output performance.