Non-covalent crosslinked hydrogels to realize renewable and re-moldable strain sensors with excellent sensing behavior

Ion hydrogels have garnered significant attention owing to outstanding softness and tissue similarity. However, disposable mechanically available hydrogels result in low resource utilization and environmental pollution. Although self-healing hydrogels are serviceable when slightly damaged, they fail to recover after experiencing extreme conditions. Therefore, exploring renewable hydrogels effectively recycles the materials and contributes to preparing functional materials. Herein, a hydrogen-bond crosslinked polyvinyl alcohol/gelatin/tannic acid hydrogel (PGTH) was fabricated, allowing complete remolding without any additives. After the Fe3+ ions were introduced into PGTH hydrogels, the strain sensors with adhesion, freezing-resistance, biocompatibility and antibacterial properties were produced. The strain sensors based on the PGTFH showed excellent strain-sensing performance, including considerable sensitivity (GF = 1.93), exceptional linearity (R2 = 0.996), fast response (102 ms) and signal repeatability (>250 cycles). Minor and major motions (the action “saying”, “drinking” and joint bending) were detected and distinguished, which demonstrated their promising application prospects in next-generation green flexible devices for health care, motion monitoring and speech recognition.