Solvent-Free And Skin-Like Supramolecular Ion-Conductive Elastomers with Versatile Processability for Multifunctional Ionic Tattoos And On-Skin Bioelectronics.

Development of stable and biocompatible soft ionic conductors, the alternatives to hydrogels and ionogels, will open up new avenues for the construction of stretchable electronics. Here, w e report a brand-new design, encapsulating a naturally occurring ionizable compound by a biocompatible polymer via high-density hydrogen-bonds, resulting in a solvent-free supramolecular ion-conductive elastomer (SF-supra-ICE), which eliminates the dehydration problem of hydrogels and possesses excellent biocompatibility. The SF-supra-ICE with high ionic conductivity (> 3.3×10 S m ) exhibits skin-like softness and strain-stiffening behaviors, excellent elasticity, breathability, and self-adhesiveness. Importantly, the SF-supra-ICE can be obtained by a simple water evaporation step to solidify the aqueous precursor into a solvent-free nature. Therefore, the aqueous precursor can act as inks to be painted and printed into customized ionic tattoos (I-tattoos) for the construction of multifunctional on-skin bioelectronics. The painted I-tattoos exhibit ultra-conformal and seamless contact with human skin, enabling long-term and high-fidelity recording of various electrophysiological signals with extraordinary immunity to motion artifacts. Human-machine interactions are achieved by exploiting the painted I-tattoos to transmit the electrophysiological signals of human beings. Stretchable I-tattoo electrode arrays, manufactured by the printing method, are demonstrated for multichannel digital diagnosis of the health condition of human back muscles and spine. This article is protected by copyright. All rights reserved.