Ion-Conductive Hydrogels with Adhesion and Self-Healing Properties for Flexible Wearable Sensors

The application of flexible sensors in long-term wearable activity and micro-expression monitoring is limited by signal drift due to interface delamination, material damage, and insufficient sensitivity. To address this challenge, an ionically conductive hydrogel (PAMTC-Zr) integrating self-adhesion, self-healing, and high sensitivity enabled by its nanoscale features was developed in this study using digital light processing (DLP) three-dimensional (3D) printing. This hydrogel was developed based on a copolymer network of acrylamide and core−shell nanostructured tannic acid-coated cellulose nanocrystals (TA@CNC) that provide abundant nanoscale interactions. The hydrogel-based sensors accurately detected intense movements of joints, such as fingers and wrists, while precisely distinguishing subtle movements, such as smiling and cheek bulging. The integration of this hydrogel with DLP 3D printing for the fabrication of customized curved surfaces, holds promise for the developing conformable, real-time, multimodal skin patches. This study provides a practical nanoscale design strategy for developing next-generation flexible health monitoring sensors that can simultaneously monitor macroscopic movements and microscopic facial expressions.