Biomaterials‐Based Hydrogel with Superior Bio‐Mimetic Ionic Conductivity and Tissue‐Matching Softness for Bioelectronics

Abstract Ionic conduction is a crucial property for electronic biomaterials used in bioelectronics, as the biological systems rely on ions to conduct electricity. Currently, biomaterials‐based functional hydrogels emerged as a promising building block for bioelectronics owing to their natural biocompatibility. However, two critical challenges faced by this type of hydrogel are their low ionic conductivity and unmatched mechanical modulus with soft tissues, which are inherently related to their complex biopolymer chains. Here, by mimicking the ion‐accelerating effect of ion channel receptors in neuron membranes, a biomaterials‐based ionic hydrogel (BIH) is developed, which offers a high ionic conductivity of 7.04 S m −1 , outperforming conventional chitosan, cellulose, agarose, starch, and gelatin based ionic hydrogels. The sulfonate groups and quaternary ammonium groups on zwitterionic side chains of poly (sulfobetaine methacrylate) (pSBMA) construct artificial cation and anion channels, respectively. The highly branched polymer structure of pSBMA reduces chain entanglement and lowers the Young's modulus of BIH to 7.2 kPa. Compared with traditional biomaterials‐based hydrogels, the BIH simultaneously possesses excellent ionic conductivity and tissue‐matching softness. Such BIH offers substantially higher quality of electrocardiogram and electromyogram signals than those of commercial electrodes.