High-strength, transparent, self-healing, conductive histidine hydrogel for flexible electrical sensors

It is a great challenge to achieve hydrogels with robust mechanical strength, high elasticity, superior electrical conductivity and transparency for the application of flexible sensors. In this study, polyacrylicacid/histidine/AlCl 3 (PAA/His/Al 3+ ) hydrogel has been synthesized for the first time without any chemical crosslinking agents. The network structure was constructed via one-pot free radical polymerization by exploiting the carboxyl groups of acrylic acid and the carboxyl and amino functionalities of histidine that coordinate with Al 3+ ions. This hydrogel possesses high transparency, excellent mechanical properties (with a tensile elongation greater than 1400 %, a tensile strength up to 1.35 MPa, and a toughness exceeding 7.28 MJ m −3 ), good self-healing ability (with a self-healing tensile length greater than 76 % within 10 min), and a relatively high ionic conductivity (∼0.68 S m −1 ). The hydrogel exhibits stable and potent electrical signal responses to various mechanical stimuli, including puncture, impact and bending deformation. This material has great potential in the next-generation flexible electronics field and broad application prospects in the field of human-computer interaction.