Natural gelatin hydrogel active sensor based on ion–electron dual-pathway synergistic conduction

Abstract Conventional hydrogel sensors demonstrate suboptimal environmental sustainability, as their ionic conduction becomes severely impeded under adverse conditions (e.g. sub-zero temperatures or low-humidity regimes), leading to progressive signal attenuation or output failure. This research utilizes biodegradable materials to dope natural gelatin hydrogel with multiple substances, integrated with an optimized dynamic cross-linking methodology, reinforcing the hydrogel’s mechanoelectrical properties. This synthetic strategy confers superior environmental compatibility while enhancing structural integrity. Additionally, patterned conductive ink electrodes were constructed on its surface through a screen-printing technique to fabricate a single-electrode triboelectric nanogenerator. The resultant device uniquely achieves efficient synergy between ion conduction and electron conduction. While extreme environmental conditions impede the ionic conduction pathway, the electronic conduction pathway remains capable of effectively sustaining the transmission of electrical signals. Synergistic operation of dual pathways transcends inherent limitations of ionic-only conduction, ensuring robust electrical signal output under adverse conditions. The material modification substantially improved the hydrogel’s thermal stability (from 30 °C to 44 °C) and cyclic reusability. Experimental results confirm the device’s excellent dynamic response characteristics, sustaining stable electrical signal output under continuous vibrational loading. By leveraging its excellent biocompatibility, the hydrogel sensor can be directly attached to human joints to enable dynamic tracking of joint motion.