Energy harvesting and forced vibration of flexoelectric hydrogel-based triboelectric spherical cap microgenerators

Abstract

Wearable electronics and microsystems using flexoelectric hydrogel-based triboelectric spherical cap microgenerators have a primary application in energy harvesting. Using mechanical energy derived from environmental vibrations or human motion, small devices, sensors, and medical implants are powered by electrical energy. An investigation of advanced energy harvesting and nonlinear forced vibration characteristics of sandwich spherical cap triboelectric microgenerators is presented as the main contribution of this work. The microgenerator structure is innovatively designed with a hydrogel core, sandwiched between polydimethylsiloxane (PDMS) layers and flexoelectric materials on the top and bottom surfaces. The strain gradient theory incorporates size effects, which are essential to accurate microscale modeling. A complex interaction between mechanical and electrical fields can be captured by using Hamilton’s principle and higher-order shear deformation theory (HSDT). A precise and efficient numerical analysis is achieved using the differential quadrature method (DQM) and Newmark approach to solve these coupled electromechanical equations of motion. Taking surface stresses into account, the maximum dynamic deflection, output voltage, and generated electrical power decreased by 23%, 22%, and 40%, respectively. Additionally, increasing the core-to-polymer skin thickness ratio led to a 77% increase in maximum dynamic deflection and a 2.75-fold increase in output voltage.