Intrinsically Nonswellable Multifunctional Hydrogel with Dynamic Nanoconfinement Networks for Robust Tissue‐Adaptable Bioelectronics

Developing bioelectronics that retains their long‐term functionalities in the human body during daily activities is a current critical issue. To accomplish this, robust tissue adaptability and biointerfacing of bioelectronics should be achieved. Hydrogels have emerged as promising materials for bioelectronics that can softly adapt to and interface with tissues. However, hydrogels lack toughness, requisite electrical properties, and fabrication methodologies. Additionally, the water‐swellable property of hydrogels weakens their mechanical properties. In this work, an intrinsically nonswellable multifunctional hydrogel exhibiting tissue‐like moduli ranging from 10 to 100 kPa, toughness (400–873 J m(−3)), stretchability (≈1000% strain), and rapid self‐healing ability (within 5 min), is developed. The incorporation of carboxyl‐ and hydroxyl‐functionalized carbon nanotubes (fCNTs) ensures high conductivity of the hydrogel (≈40 S m(−1)), which can be maintained and recovered even after stretching or rupture. After a simple chemical modification, the hydrogel shows tissue‐adhesive properties (≈50 kPa) against the target tissues. Moreover, the hydrogel can be 3D printed with a high resolution (≈100 µm) through heat treatment owing to its shear‐thinning capacity, endowing it with fabrication versatility. The hydrogel is successfully applied to underwater electromyography (EMG) detection and ex vivo bladder expansion monitoring, demonstrating its potential for practical bioelectronics.