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 Ca2+ 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.