Predicting the Output of a Triboelectric Energy Harvester Undergoing Mechanical Pressure

Energy harvesting using a triboelectric nanogenerator (TENG) has been a major area of research in the recent years in order to harvest mechanical energy in different scales. High energy conversion efficiency, broad range of application in different systems and relatively easy fabrication process are among the factors demonstrating essential needs for TENG technology development. Performance of a TENG could be affected by many factors such as the frequency of vibration and the surface charge density. As a key factor in improving the power output of TENGs, surface charge density could be modified by the selection of proper charging materials and by increasing the contact area between the tribo-pairs. Although there have been numerous studies analyzing the performance of different tribo-pairs and different interfacial structures for a TENG, a systematical analysis of the contact phenomena between the interfacial structures in order to investigate the effects of different surface properties and structures such as, surface roughness, dielectric properties or the presence of nanostructures is still not available. In the current study, systematical numerical simulations have been performed on the adhesive contact behavior of the macro/nanostructures at the TENG interface. An interaction potential has been used to represent the adhesive interactions while surface deformations are coupled using half-space Green’s function. Furthermore, effects of the deformation of the interfacial structure on the performance and output of the TENG has been investigated by developing a theoretical model for a vertical-contact-mode TENG using a mass-spring system to represent the motion of the moving electrode. Coupling the theoretical model to the instantaneous deformation of the interfacial structure, real-time output of the TENG in terms of short-circuit voltage and open-circuit current has been studied in response to a predefined pressure input. The results of the current study demonstrate the effects of the deformation of the interfacial structure on the output characteristics of TENGs during the transition between partial-contact to full-contact modes. Numerical simulation results represent acceptable correlations with previously reported experimental data. The simulation package developed in this study is capable of simulating the contact behavior of the interfacial structure and predicting the deformed geometry.