Ultrafast Self-Healing Conductive Hydrogels with Dual Dynamic Networks for Multimodal Wearable Sensing

As a representative class of soft functional materials, conductive hydrogels have attracted considerable research attention in strain-sensing applications. However, achieving the simultaneous combination of mechanical strength, self-healing ability, and self-adhesion continues to present a significant challenge in the hydrogel design. In this study, rapid self-healing PAA/AG-B-Al 3+ hydrogels with a dual network were prepared by using poly(acrylic acid) (PAA) as the primary network and agarose (AG) as the secondary network. The synergistic presence of tannic acid, borax, and Al 3+ ions enabled dynamic bonding through hydrogen bonds, metal-coordination bonds, and borate ester bonds, which facilitated high self-healing efficiency (96.8% within 2 h) while imparting mechanical strength with good recovery and fatigue resistance. The hydrogel exhibited outstanding sensing capabilities, demonstrating durability, reliability, and a high sensitivity with a gauge factor (GF) of 11.26. It accurately and in real time monitored not only daily human movements (knuckles, wrists, and facial expressions) but also vital signs (respiration and pulse), exhibiting its versatility in patient care. The hydrogel demonstrated multifunctional applicability as an environmental sensor and a binary signal transmitter. These properties highlight its considerable potential for flexible wearable electronics and advanced human-computer interfaces.