Bioinspired Ultratough and Rapidly Responsive Hydrogels Empower Silent Communication.

The development of sustainable flexible electronics is hindered by a lack of sensing materials that synergize eco-friendliness, robust mechanical properties, and reliable electromechanical responsiveness. While starch-based hydrogels present a promising sustainable alternative, their widespread application is limited by inherent brittleness and significant signal hysteresis. Here, a molecular engineering strategy is proposed to address these limitations. Porous starch is first obtained through a gradual solvent exchange process to enhance chain accessibility. Protocatechuic acid (PCA) is then covalently grafted onto the starch backbone via EDC/NHS-mediated esterification, introducing dynamic hydrogen-bonding and π - π interaction motifs. By optimizing the ratio between PCA-modified starch and polyacrylamide (PAM), a bioinspired hydrogel with exceptional toughness and rapid electromechanical response is achieved. The resultant hydrogel exhibited pronounced strain-dependent resistance behavior, enabling its integration into a wireless wearable human-machine interface. To ensure robust decoding against motion-induced noise, a finite state machine (FSM)-based algorithm is employed for adaptive signal segmentation, achieving a character-level accuracy of 99.2% in trials with healthy subjects (n = 10). This work not only introduces a high-performance, sustainable hydrogel platform but also demonstrates a practical route toward inclusive and language-independent human-machine communication.