Influence of cellulose on the properties of physically cross-linked poly(vinyl alcohol)/Agar double network hydrogels and investigation of multifunctional flexible sensors

With the slogan "double carbon target" coming into the public's view, green, healthy, non-toxic and harmless hydrogel flexible sensors have become one of the research subjects of many staff. But most hydrogels need a crosslinking agent to complete polymerization. In this work, a PVA (poly (vinyl alcohol))/Agar hydrogel material was designed to form three-dimensional reticulated composite hydrogels with a variety of cellulose, and more green and healthy citric acid was used instead of PVA crosslinker to promote hydrogel polymerization. Through the test of four kinds of cellulose, it was found that PVA/HPMC ((Hydroxypropyl)methyl cellulose)/Agar hydrogel has the most outstanding performance, its mechanical property is 1.77 MPa, its elongation at break can reach 766 %, and it has good recovery performance, fatigue resistance and good adhesion. After it is applied to the flexible hydrogel sensor, its gauge factor value is as high as 5.94 under the strain of more than 200 %. When simulating human skin and detecting human motion, the electrical signal changes sensitively and repeatedly, and has a good response when testing temperature and humidity. PVA/HPMC/Agar hydrogel provides a more healthy solution for flexible electronic devices.