3D visualization microscope of TENG contact interface based on astigmatic imaging

The triboelectric nanogenerator (TENG) is a mechanical device that can collect mechanical energy from the contact and separation of different materials. Due to the short distance of charge transfer, the characterization of the micro-contact state under localized stress has become an urgent issue in the study of TENG’s contact electrification mechanism. Most of the contact surfaces of TENG are curved surfaces, and there is a lack of effective means to characterize the contact state of curved surfaces. In this article, a technique based on astigmatic imaging principle is provided to visualize the three-dimensional contact interface of TENG, using polydimethylsiloxane (PDMS) and butyronitrile film with rough surface as TENG. Through this technique, the three-dimensional deformation of its contact interface was observed and the three-dimensional effective contact area was calculated. The comparison of current density generated at different pressing pressures verified that larger contact area leads to higher current density, which applies to the law in 3D contact interfaces as well. Visualizing conformal contact interfaces for TENG provide a powerful tool for analyzing the charge transfer-contact separation phase coordination mechanism, providing a new route approaching larger output efficiency. In addition, this technology offers possibility for characterization of TENG with both-side deformable, which abandons the requirements of the rigid contact surface in the total reflection scheme and is much more applicable for organic TENG. [Display omitted] •Origin of the contact pressure-dependent performance of TENGs investigated.•3D visualization of the TENG contact interface is realized.•The effect of pressure on the output of TENG is the expansion of the actual contact area.•Fusion of contact sites under Conformal contact was found.