Conductive Hydrogel With Self-healing Property For Flexible Sensors

Conductive hydrogels have been widely used in flexible electronic skin,wearable devices and soft robots,due to their excellent conductive properties and flexibility.However,the flexible electronic devices based on this kind of conductive hydrogels often have many problems such as wear and tear,water loss and serious aging,which affect their service life and limit their application and promotion.Based on this situation,in this paper,a composite hydrogel with good electrical conductivity,mechanical properties,unique photothermal properties,high response sensitivity and excellent healing properties was constructed and its application in flexible sensor parts was explored.The concrete contents include the following two parts :(1)Based on hydrogen bonding,Polyaniline/Polyvinyl alcohol(PANI/PVA hydrogel)was prepared by redox method and freeze-thaw method.Using the excellent photothermal conversion characteristics of PANI and the multiple hydrogen bonding of PVA hydrogel,various healing methods of hydrogels were realized.Using the self-healing method,it only takes 3 minutes after shearing and bonding to heal quickly,and the healing efficiency is up to 68%;after 6h,the healing efficiency is as high as 96%.Secondly,the material has a high electrical conductivity(12.6s/m),which can be used to monitor the movement signals of human knuckles,elbow joints,knee joints and chewing behavior.This indicates that the hydrogel can be used as a flexible sensor device of a flexible strain sensor with potential application prospects.In addition,relying on the unique photothermal properties of polyaniline,the hydrogel has important application potential in light-controlled switches.(2)PVA-PMETA/ PNa SS-Aloe Vera double network hydrogel(P-MN-A double network hydrogel)was constructed by the combination of free radical polymerization and freeze-thaw method and based on the water-absorbing properties of acrylic ion hydrogel and the moisturizing properties of Aloe vera gel.Compared with PMETA/ PNASS ion hydrogel(MN ion hydrogel)of the single network,P-Mn-A hydrogel of the double network has excellent mechanical properties,with the maximum stress up to 1.33 MPa.In addition,compared with MN ion hydrogel,the P-MN-A double network hydrogel has a good anti-water loss performance,which increases the water retention performance by 2.4 times within 2 days,and reduces the natural water loss efficiency by 3.7 times.Based on the excellent electrical conductivity of P-MN-A double network hydrogel,the application of P-MN-A as a kind of strain sensor in wearable devices was explored,which realized accurate monitoring of pulse and speech recognition to accurately distinguish words and sentences.These results indicate that the hydrogel can be used as a flexible strain sensor in human-computer interaction,health diagnosis and intelligent robot electronic skin,and provide a new idea for the construction of flexible electronic devices with high stability and high sensitivity.