Chrysalis-inspired high-toughness low-modulus conductive hydrogel sensor for intelligent sensing

Hydrogels displaying both high toughness and flexibility hold substantial practical value. However, it has been challenging to achieve these properties simultaneously. To address this challenge, we developed a special structure hydrogel named PAB-S inspired by chrysalis shell. Astragalus polysaccharide (AP) was copolymerized with polyvinyl alcohol (PVA) and betaine hydrochloride (BH) to prepare a low-modulus hydrogel, PAB. Subsequently, surface modification of the PAB hydrogel using sodium phytate (SP) resulted in the formation of the "shell" structured PAB-S hydrogel. The fracture strength of the shell-structured hydrogel increased by about 0.8 MPa. Meanwhile, PAB-S had a maximum tensile strain of 418 %, a toughness of 6.82 MJ/m3, and a modulus of elasticity of approximately 0.6 MPa. In addition, PAB-S hydrogel offers high strain sensitivity (GF up to 4.7), ultra-low response time of 20 ms. Finally, leveraging 2.4G communication technology and a deep learning (1D-CNN) algorithm, advanced functionalities such as wireless remote intelligent control, and deep learning-based finger grip disorder identification were realized using the PAB-S hydrogel sensor. The PAB-S hydrogel sensor holds promising prospects for applications in fields including deep learning, intelligent sensing, medical rehabilitation, and human–machine synchronization.