Enhanced energy harvesting ability of polydimethylsiloxane-BaTiO3-based flexible piezoelectric nanogenerator for tactile imitation application

Highlights: • Both doping and structure modification can boost the performance of the PENG. • A good contact between the flexible electrodes and piezoelectric layers is realized during bending and folding of the device. • The PENG attached on human-skin surface can be used as tactile perception by the aid of the external circuit. The development of wearable piezoelectric nanogenerator (PENG) has recently drawn extensive attention, especially in selecting lead-free piezoelectric materials with high piezoelectric coefficients. Barium Titanate (BTO) is a kind of environment-friendly piezoelectric ceramics. PENGs derived from BTO based piezo-fillers have recently attracted broad concern. However, the exploration of flexible electrodes and the application of wearable PENGs functioned with imitating tactile have usually been ignored in the pursuit of high output performance. Herein, The porous piezoelectric fillers composed of 0.82Ba(Ti_0.89Sn_0.11)O₃-0.18(Ba_0.7Ca_0.3)TiO₃ are prepared by a freeze-drying method, and then the polydimethylsiloxane (PDMS) is filled into the micropores of the piezoelectric ceramics, forming a distinctive 3D interconnected structure with evenly distributed inorganic piezoelectric materials. Both doping and structure modification can boost the output performance of the BTO-based PENG, from which the rational doping plays a major role in enhancing the electrical output in the current PENG system. To realize fully flexible piezoelectric nanogenerator (PENG), sliver nanowires network integrated with PDMS is adopted as the flexible electrodes, which was fabricated by the techniques combining vacuum filtration with subsequent dry transfer process. The PENG can deliver a maximum open-circuit voltage (V_OC) of 39 V and short-circuit (I_SC) current of 2.9 μA under a vertical force of 35 N at 2 Hz, with the maximum instantaneous power of 24.2 μW. Moreover, the device can effectively exhibit electric output signal whenever subjected to external pressing or bending stress. The output performance of the PENG at via vertical pressing stress is higher than that bending stress, which is also confirmed by COMSOL simulation. The PENG can not only be employed to harvest biomechanical energy such as digital joints movement, but also display a potential for a tactile perception. This work has established a deep association between lead-free ceramic and wearable imitated touch reception sensors by virtue of flexible PENG, which will paint a magnificent picture for flexible electronics.