Abstract
This letter presents a monolayer onion epidermis as an ultrathin substrate for the development of dry electrodes used in electrical impedance spectroscopy (EIS), offering biocompatibility, flexibility, and high fidelity. The dry electrode is fabricated by sputtering a 100 nm layer of molybdenum onto the hydrophilic side of the epidermis membrane. Optical characterization confirms the structural integrity and quality of the thin metal film. Electrical characterization reveals a low sheet resistance of 151.28 ± 0.08 Ω/m2, and experimental EIS studies demonstrate the electrode's enhanced electrical characteristics and capability to acquire impedance spectra from various fruits. In addition, durability tests over six months show comparable performance to commercial electrodes. This biocompatible electrode offrs a promising, cost-effective, and sustainable solution with reduced resource utilization, ideal for agrifood and wearable electronics applications.