PVA/PA/H₃PO₄ Hydrogel Films with Ultrawide Pressure and Strain Sensing Range via Facile Fabrication Method

Abstract Hydrogel, as a sensitive element of flexible sensor, can change its resistance or capacitance according to mechanical deformation and provide critical service for the Internet of Things (IOT). However, it is a challenge to fabricate a hydrogel that simultaneously possesses excellent mechanical properties and great conductivity via low‐cost and simple method. Herein, one‐pot and solution‐casting methods were adopted to fabricate hydrogel film efficiently. Phosphoric acid (H₃PO₄) plays the role of both proton source and plasticizer can that improves the conductivity and flexibility of hydrogel. Phytic acid(PA) with abundant hydroxyl groups can form physical crosslink with PVA(polyvinyl alcohol) chain via hydrogen bond, thus increasing rigidity. H₃PO₄ and PA are used for reinforcing the conductivity and mechanical properties of PVA hydrogel by exploring the best mass fraction. This hydrogel, i.e., PVA/PA/H₃PO₄, possesses 3500% elongation, 2500% effective sensing range, great conductivity of 4.2467 S m⁻¹, fast response/release time(65ms/91ms), outstanding durability (10,000s) for strain sensor and great detection limit of 1250 kPa and 3.85 kPa⁻¹ sensitivity for pressure sensor. The great performance proves that hydrogel is capable for practice applications such as identifying pressure distribution and monitoring human activity situation. This method provides a new idea for the low‐cost and large‐scale fabrication of flexible sensors.