Research On Composite Conductive Hydrogels For Pressure Sensing Devices

Hydrogel is a cross-linked hydrophilic polymer with high water absorption properties.Among them,conductive hydrogels(ECHs)have a variety of biological properties(such as water retention,biological activity,self-healing,etc.)similar to biological tissues,and also have excellent electrical conductivity,so they have always been the frontier of the development of“intelligent conductive biomaterials”.However,ECHs are still under investigation that can achieve desired conductivity and mechanical properties(such as toughness and stretchability)at the same time.Polyacrylamide hydrogel(PAM)has good biocompatibility,is non-toxic and environmentally friendly,and can be widely used in biomedicine and other fields.However,PAM hydrogel has low mechanical strength and poor water retention.Therefore,how to prepare functionalized PAM hydrogels is currently an urgent problem to be solved.Graphene has excellent physical and chemical properties,including high specific surface area,excellent mechanical strength,excellent thermal conductivity and electron transport capabilities.Another branch of graphene research is graphene oxide(GO).The edge of the GO sheet contains a large number of oxygen functional groups.These oxygen functional groups can be used as effective sites for the chemical modification or functionalization of GO.The raw materials of polyaniline are easily available,low in cost,simple in preparation,and good in redox reversibility.However,polyaniline has poor solubility and limited processability.At present,researchers have prepared and studied various graphene and polyaniline composite materials.Most of these composite materials have the characteristics of graphene and polyaniline at the same time.However,in most composite materials,graphene and polyaniline are connected by non-covalent bonds,and there are relatively few reports on the covalent linkage of graphene and polyaniline and have not been systematically developed.Graphene grafted polyaniline(r GO-g-PANI)composite material was synthesized,and the successful composite of polyaniline and graphene oxide was proved by XPS and FT-IR.Then by changing the concentration of GO and r GO-g-PANI dispersions,PAM composite hydrogels filled with conductive materials of different proportions were prepared,and the mechanical and dielectric properties of the composite hydrogels were characterized.The electrical parameters of different proportions of conductive fillers and different thicknesses of hydrogels in the frequency range from 1 Hz to 10~7Hz were obtained through dielectric relaxation tests.GO/PAM hydrogel was assembled into an organic thin film transistor device(OTFT),and the response to pressure was measured.