Adhesive-Free Hydrogel Bioelectronics Enabled by a Template-Directed Assembly of Metallic Nanofibrous Network

Over the past decade, conductive hydrogels have received great attention as tissue-interfacing electrodes due to their soft and tissue-like mechanical properties. However, a trade-off between robust tissue-like mechanical properties and good electrical properties has prevented the fabrication of a tough, highly conductive hydrogel and limited its use in bioelectronics.<br/>Here, I present a new synthetic method for the realization of highly conductive and mechanically tough hydrogels with tissue-like modulus. I employed a template-directed assembly method, which enables the arrangement of a disorder-free, metallic nanofibrous conductive network inside a highly stretchable hydrogel network. The resultant hydrogel exhibits exceptionally high conductivity (247 S/cm), high stretchability (&gt;600%), and tissue-like Young’s modulus (35 kPa). Furthermore, it can provide tough adhesion (800 J/m2) with diverse dynamic wet tissue after chemical activation. In addition, its biocompatibility in vivo was confirmed, which makes our hydrogel an ideal bio-interfacing electrode for bioelectronics. For the first time, this hydrogel enables suture-free and adhesive-free, high-performance hydrogel bioelectronics. I successfully demonstrated ultra-low voltage neuromodulation and high-quality epicardial electrocardiogram (ECG) signal recording based on in vivo animal models. This template-directed assembly method provides a new platform for hydrogel interfaces for various bioelectronic applications. I will discuss the details of the synthesis of T-ECH and its application for adhesive-free hydrogel bioelectronics.