Stretchable, Breathable and Skin‐conformal Nanofilm‐based Epidermal Dry Electrodes for Electrophysiological and Motion Monitoring

ABSTRACT To meet the requirements for long‐term electrophysiological signal recording and fine muscle motion monitoring, the development of ultrathin, stretchable, skin‐conformal, and breathable dry electrodes is highly desirable. In this work, we present a flexible crosslinked nanofilm coated with silver nanowires to fabricate ultrathin dry electrodes. The nanofilm is synthesized through air‐liquid interfacial polymerization using a biocompatible polyethylene glycol (PEG)‐containing linker and a calix[4]arene derivative. The incorporation of acyl‐hydrazone and PEG moieties ensures strong adhesion and excellent skin conformality. After depositing silver nanowires on one side, the resulting electrode—with a thickness of only 400 nm—demonstrates a relatively low Young's modulus of 3.55 MPa, a sheet resistance of 4.95 Ω sq −1 , great adhesion (36 N m −1 ), high gas permeability and low cytotoxicity. Multimodal sensing experiments confirm that nanofilm electrodes can detect subtle motions when attached to various body parts, including finger, elbow, wrist, knuckle, and knee. Furthermore, we integrate nanofilm electrodes with a bio‐signal recording system, successfully acquiring high‐quality electrocardiograms and electromyograms, as well as monitoring large muscle and fine muscle motions, where the latter is particularly challenging to record. Moreover, the combination of a deep learning algorithm enables the recognition of finger movements with high accuracy.