2-Second In-Situ Formation of Adaptive Electronic Bio-Skin Enabled by Metal Coordination

Electronic skin (E-skin), a conformal human-machine interface, holds promise for healthcare monitoring and personal electronics. However, traditional fabrication methods face challenges of reliance on non-sustainable materials, intricate and time-consuming processes, and material softness-induced fragile transfer to target substrates. Inspired by "milk skin" phenomenon, we developed a rapid "dipping-dipping" molecular assembly method to in-situ fabricate cellulose-based bio-skin within seconds, exhibiting ultra-thin, high conformal, shape-customizable, degradable, and low impedance performances. This technique immerses substrates sequentially into carboxymethyl cellulose (CMC) and Cu(II) solutions, leveraging strong metal-coordination interactions. Membrane formation efficiency, influenced by the oxidation of metal ions, follows the order: Cu(II) > Fe(II) > Ca(II). CMC-Ag(I)/CMC-Cu(II) form stable membranes, whereas CMC-Fe(II) is fragmented structures, and CMC-Mg(II)/CMC-Ca(II) remain in solution. This adaptable method extends to other biomacromolecules like methylcellulose and carboxymethyl chitosan, broadening applications. The bio-skin enables real-time monitoring of electrocardiograms (ECG), electrooculograms (EOG), electroencephalograms (EEG), and electromyograms (EMG), showcasing its potential for wearable, biocompatible electronics in healthcare.