Surface-Modified Nanostructured Piezoelectric Device as a Cost-Effective Transducer for Energy and Biomedicine

Flexible polymer–metal oxide nanocomposites with multiwalled carbon nanotube (MWCNT) films are fabricated using poly(vinylidene fluoride) (PVDF) as the bulk matrix material with three-dimensional (3D) lithium-doped zinc oxide (Li-ZnO) as a filler. Li-ZnO is synthesized hydrothermally followed by surface modification with polyethylene glycol (PEG). PEG coating serves as an effective solution for avoiding costly electrical poling and enhances the proportion of the PVDF β phase, while MWCNTs act to increase conductivity and to reinforce the composite during mechanical stressing. The piezoelectric composite is fabricated with 12 wt% surface-modified Li-ZnO with 0.2 wt% MWCNT relative to the bulk PVDF. The fabricated composite is tested with different body motions and in different environments. The highest obtained value of open circuit voltage is 10.1 V and 2740 µA amperometric alternating current with bending motions. It is also observed that the electrical signal fluctuates by ≈200 µA due to microrelaxation and microstressing under constant stress conditions. The piezoelectric nanocomposite shows a linear response to a gradual increase in normal stress.