Biomineral calcium-ion-mediated conductive hydrogels with high stretchability and self-adhesiveness for sensitive iontronic sensors

Ion-conductive hydrogels combining high-performance mechanical properties, high conductivity, and self-adhesion are ideal for iontronic sensors, but their fabrication remains a challenge. Here, we present a transparent and highly ion-conductive hydrogel that integrates high strength, stretchability, and self-adhesiveness for iontronic sensors. The hydrogel is prepared by introducing biomineral calcium ions into a polyacrylamide-sodium carboxymethyl cellulose (PAM–CMC) crosslinked network. The presence of Ca 2+ not only induces the formation of dynamic crosslinked structure, endowing the hydrogel with notable mechanical properties (maximum strain of 1,480% and stress of 276 kPa), but also results in high ion conductivity (1.4 S·m −1 ). The hydrogel also exhibits strong adhesion with various substrates. Fabricated hydrogel-based sensors are highly sensitive to strain and stress changes with wide sensing ranges and can be used to detect complex human activities. • Transparent and highly ionic-conductive hydrogels utilizing Ca 2+ • Integration of high strength, stretchability, and self-adhesiveness • Detection and recognition of complex human activities with high sensitivity and stability High-performance, ion-conductive hydrogels are necessary for iontronic sensors. Bai et al. design a transparent and ion-conductive hydrogel with high strength, stretchability, and self-adhesiveness utilizing biomineral Ca 2+ to regulate the crosslinked network structure of hydrogel. The material can be incorporated into iontronic sensors with high sensitivity and stability.