Incorporation of inorganic piezoelectric ceramic nanoparticles into a highly elastic polymer matrix is an effective method to develop self-powered sensors and energy harvesters. Herein, a piezoelectrically enhanced nanogenerator (NG) obtained by dispersing lead-free BaTiO3 piezoelectric nanoparticles into elastic polydimethylsiloxane and further surface-modifying with a neoteric mosaic structure for self-powered sensing is proposed. The composites fabricated through this facile and low-cost approach exhibit enhanced voltage by a factor of 1.5 relative to those without modification and display improved mechanical properties with increased elongation at break (failure strain of 150%). The improved performance is mainly attributed to the embossed mosaic structure on the surface, which is theoretically verified by multiphysics simulation. The NGs exhibit highly sensitive and stable piezoelectric output under contact and noncontact working modes and can be applied to detect human vital signs, including bending of fingers and wrists, and various breathing activities, demonstrating wide applications in flexible and smart wearable electronics. The design of the neoteric mosaic structure could be extended to other composite-based NGs, offering significant advantages for the rational design of flexible electronics.
Keywords: flexible sensor; health monitoring; mosaic structure; piezoelectric composites; surface modification.