Agar-modified gelatin/polyvinyl alcohol-based tough hydrogels for 3D printing to prepare multifunctional sensors and...

Gelatin/polyvinyl alcohol-based conductive hydrogels hold great potential in wearable electronics but face challenges such as weak mechanical properties and poor freeze resistance. To overcome these limitations, this study successfully employed a multi-network construction strategy to prepare a zwitterionic multifunctional hydrogel based on gelatin-polyvinyl alcohol-betaine‑sodium alginate (Gel-PVA-Betaine-SA) and modified with agar. This hydrogel material, through the synergistic combination of gelatin, agar, PVA and sodium alginate, and the introduction of zwitterions/small molecules such as betaine and glycerol for synergistic regulation, exhibits a variety of excellent properties. Specifically, the hydrogel ink possesses good 3D printing capability, the hydrogel adhesive exhibits adhesive properties, and the hydrogel material can maintain its flexibility at low temperatures (-20 °C). Furthermore, when used as a flexible sensor, the hydrogel material can achieve dual-response functionality to mechanical deformation (GF = 1.994-7.50) and the environment (temperature-humidity) and demonstrates high stability in human motion monitoring. Finally, a supercapacitor assembled with Gel-PVA-Betaine-SA hydrogel as an electrolyte exhibits excellent electrochemical performance and can stably undergo 40,000 charge-discharge cycles. This study provides new ideas for the application of multifunctional hydrogels in the fields of wearable devices, sensing technology, and energy storage devices.