Preparation And Properties Of Graphene Conductive Hydrogel

With the rise of new fields such as wearable devices,human health monitoring and artificial intelligence,flexible sensors have received widespread attention in various industries.The materials for making flexible sensors must have high sensitivity,excellent mechanical properties,good electrical conductivity and biocompatibility.Conductive hydrogels combine conductive fillers with the excellent properties of hydrogels,making them ideal materials for constructing flexible sensors and wound dressings.However,conductive gel has some problems such as poor mechanical properties and low sensitivity.In this paper,three kinds of conductive hydrogels with excellent properties were prepared by reducing Graphene Oxide(GO),and their applications in flexible strain sensors and wound dressings were studied.The details are as follows:(1)Using L-cysteine(L-c)as the reducing agent of GO,a conductive rGO network was obtained,and then a conductive rGO/polyvinyl alcohol(PVA)with excellent mechanical properties was prepared by the dipping method.The hydrogel shows a fast and stable resistance change response under small strains.And 70 cycles of compression under 5%normal strain,showing stable strain response performance.At the same time,the hydrogel has different resistance change responses to different shear strains,which can be distinguished between small(0.1%)and large(1%))shear strain response performance.However,the hydrogel has insufficient sensitivity to detect weak physiological signals.(2)In response to the lack of sensitivity of L-c-rGO/PVA conductive hydrogels,we replaced the reducing agent with Polydopamine(PDA)to prepare PDA-rGO/PVA conductive hydrogels.Due to the uniform dispersion of the PDA-rGO nanosheets in the hydrogel network,the hydrogel shows high sensitivity at low strains(11)and excellent linear response at high strains,which can monitor limb movement and pulse in real time beating and throat swallowing vibration,and can provide accurate and reliable monitoring for weak vital signals and human movement.These results indicate that the hydrogel has potential application value in electronic skin,biomedical implants and human motion monitors.(3)Dissolve methacryloyl chitosan(CHMA)with good solubility and biocompatibility in rGO dispersion,mix with Dextran Oxid(ODEX)solution,and obtain it under physiological conditions rGO/CHMA-ODEX hydrogel crosslinked by dynamic Schiff base bonds.The hydrogel has both the electrical activity of rGO and the biocompatibility and biodegradability of natural polysaccharides.More importantly,due to the presence of dynamic Schiff base bonds,the hydrogel has excellent injectability and self-healing ability in physiological environments.The results of animal experiments show that on the 14th day,the rGO/CHMA-ODEX hydrogel group has a smaller wound area than the CHMA-ODEX hydrogel group and the commercial film dressing(3M Tegaderm TM)control group,indicating that the hydrogel has great potential as a dressing to promote skin wound healing.