High-sensitivity, dual-mode, flexible, electrooxidized cellulose-based electronic skins with compatible mechanical properties and antimicrobial activity for wide-temperature applications

Flexible "electronic skins" ("e-skins") are crucial for robotics, healthcare and medical monitoring, but face several challenges such as sensibility, stability and temperature endurance. Herein, a novel high-sensitivity dual-mode self-powered e-skin for temperature and strain sensing is proposed using a cellulose-based ionogel and non-faradaic junction (NFJ) for wide-temperature applications. The ionogel was prepared in a facile manner using cellulose which was controllably electrooxidized without toxic solvents. It had excellent temperature endurance and good adaptability to human skin because of constructed highly entangled hierarchical multi-scale networks (EMSN). The tensile strength reached 0.349-1.145 MPa, while Young's modulus (0.542-1.057 MPa) and toughness (0.18-3.59 MJ m^-3) were compatible from -40 to 120 °C, comparable with those of human skin and the reports. Structural integrity and elasticity were maintained at -100 and 120 °C. The e-skin could achieve dual-mode sensing and exhibit superior performance such as high sensitivity (GF = 0.75), high fidelity of sensing signals at different temperatures, good stability, and antimicrobial activity. A solid-state supercapacitor using the ionogel without pressure and any other liquid electrolyte exhibited a voltage window of 0.6 V and a power density of 210.00 W kg^-1. We have supplied a novel strategy to develop sustainable sensors with biocompatibility for harsh surroundings.