All porous Ecoflex and SEBS-based stretchable high-performance triboelectric nanogenerator for self-powered human activity monitoring

Achieving a high output performance by expanding the surface area of triboelectric materials is key to developing triboelectric nanogenerators (TENGs) for future versatile applications. Herein, highly porous Ecoflex and styrene-ethylene-butylene-styrene (SEBS) using chloroform are introduced to improve TENG performance. The triboelectric output increases significantly with increasing porosity, which can be attributed to the increase in the contact area, dielectric constant, and electrostatic induction in the porous structure, thereby resulting in additional surface charges on the porous surface and increased surface charge density of the friction materials. The TENG can stretch by up to 550 % with the designed fabric electrode configuration. Facilitated by the increased contact area of 3D printed microstructure and porous Ecoflex substrate, the fabricated TENG demonstrates a high voltage of 2280 V, corresponding to a power density of 18.8 W m−2, which is enough to power 460 light-emitting diodes and stopwatches. Demonstration of monitoring the walking steps of patients with Parkinson's and blind people was also performed, which revealed outstanding sensing capabilities. In addition, the TENG-based self-powered sensor demonstrated an identification accuracy of 99.3 % and a motion detection accuracy of 98.2 % based on a deep learning model. Furthermore, by exploiting the outstanding ultrahigh sensitivity, the TENG was demonstrated for low-frequency football player motion monitoring. Therefore, the results of this study provide new insights into investigating porous materials and an efficient method to construct high-performance TENGs that can promote their practical application in the fields of smart healthcare and sports.