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

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. A hydrogel composed of Phytic acid (PA), phosphoric acid (H3PO4) and polyvinyl alcohol (PVA) is prepared by one‐pot method. Abundant hydrogen bonds formed by PA and H3PO4 have synergistically improved the mechanical properties of the hydrogel. Experimental results show the hydrogel has 3500% strain and 0–1250 kPa pressure range, which is higher than previous works.