Cellulose Hydrogels by Reversible Ion‐Exchange as Flexible Pressure Sensors
Shuai Zhou, Kechun Guo, Danil Bukhvalov, Xiong‐Fei Zhang, Wenzhuo Zhu, Jianfeng Yao, Ming He
Abstract
Abstract Inspired by biological camouflage strategy according to the surrounding environment, a facile method to fabricate state‐switchable cellulose hydrogels (fluid, brittle, and rigid hydrogel) driven by Ca 2+ /Zn 2+ ion exchange is reported. The high content of Ca 2+ ions leads to the formation of a rigid hydrogel (Gel‐H‐Ca 2+ ) with a great compressive strength (≈2.2 MPa) through coordination cross‐linking network, while Zn 2+ ions give the cellulose (Sol‐L‐Zn 2+ ) a fluid state by eliminating the cellulose intermolecular connections, making it possible to obtain injectable and healable hydrogels. Gel‐H‐Ca 2+ is highly oriented and anisotropic, and such flexible hydrogel can effectively monitor slight bending and pressure changes of fingers. This cellulose hydrogel will be a promising candidate for bionic and multifunctional sensors.