Highly Flexible and Transparent Polyionic-Skin Triboelectric Nanogenerator for Biomechanical Motion Harvesting

The advances of flexible electronics have raised demand for power sources with adaptability, flexibility, and multifunctionalities. Triboelectric nanogenerators are promising replacements for traditional batteries. Here, a highly soft skin-like, transparent, and easily adaptable biomechanical energy harvester, based on a hybrid elastomer and with a polyionic hydrogel as the electrification layer and current collector, is developed. By harvesting the energy in human motion, the device generates an open-circuit voltage of 70 V, a short-circuit current density of 30.2 mA m⁻², and a maximum power density of 2.79 W m⁻² in a single-electrode working mode. Further, it is demonstrated that the device can deliver power under bending, curling or by simple tapping when attached to human skin. In addition, the optimal counterpart of the polyionic layer with highest electronegativity difference is selected from a series of contact electrification materials based on a two-electrode working mode, where a flexible device with the matching counterparts is investigated. Serving as ionic conductor and electrification layer, this polyionic material shows promising application in future development of self-powered flexible electronics.