Preparation Of Polvnvrrole/Silk Fibroin Conductive Hydrogel And Its Application In Flexible Sensors

Flexible wearable electronic products have attracted widespread attention in recent years due to their special performance and huge application potential,especially in the areas of human health monitoring,friction electric nanogenerators(TENGs)and energy storage.At present,there have been many reports on flexible and stretchable electronic products.These electronic products usually disperse conductive components(such as carbon nanotubes,graphene oxide and metal nanowires)on a flexible substrate(such as water Gel,polydimethylsiloxane,etc.)for processing and preparation.Compared with flexible substrate materials such as PDMS and PET,silk fibroin has low production cost,good biocompatibility,and can be biodegraded.It has great application prospects in implantable devices.At the same time,silk fibroin can be made into various forms of matrix,such as sponge,electrospinning,membrane,hydrogel,etc.,which is easy to process.So far,there are few reports on the use of silk fibroin to prepare conductive hydrogels as flexible sensors.This research is helpful to expand the application of silk fibroin in non-traditional industries.Polypyrrole is a conductive polymer.It not only has the excellent conductivity of metals and semiconductors,but also has the flexible mechanical properties and processability of organic polymers.In addition,studies have shown that polypyrrole can promote cell proliferation and differentiation,stimulate nerve regeneration,and has good biocompatibility.Therefore,the combination of silk fibroin and polypyrrole to prepare conductive hydrogels has the feasibility of constructing flexible sensors.In this paper,silk fibroin(SF)is used as raw material,and the hydrogen peroxide/horseradish peroxidase system(H2O2/HRP)is used to catalyze the cross-linking of tyrosine residues between silk fibroin chains to form silk fibroin hydrogel(SF hydrogel).The pyrrole monomer(Py)is modified on the surface of the silk fibroin hydrogel by in-situ coating technology to prepare a silk fibroin hydrogel(Py/SF hydrogel)containing the pyrrole monomer.In-situ polymerization of pyrrole in silk fibroin gel is catalyzed by ammonium persulfate(APS)to form conductive polypyrrole/silk fibroin hydrogel(PPy/SF hydrogel);then the polypyrrole/silk fibroin hydrogel is scanned Characterization of electron microscopy,infrared,therm ogravimetric and swelling rate;then polypyrrol e/silk fibroin hydrogel is used as a sensor to sense external stimuli;finally,polypyrrole/silk fibroin hydrogel is co-cultured with L929 cells to explore the water Biocompatibility of the gel.The results show that the prepared polypyrrol e/silk fibroin hydrogel has good flexibility and can be stretched and bent appropriately.The electrical characteristics show that the hydrogel has good conductivity(0.09～0.45 S/m).The conductive gel exhibits high sensitivity(GF=2.3)during the stretching process,and can ensure stable output of electrical signals under different stretching frequencies and stretching strains.The conductive hydrogel can detect a series of human movement indicators such as finger bending,knee bending,and elbow bending.In addition,polypyrrol e/silk fibroin hydrogel has the effect of promoting cell proliferation to a certain extent,indicating that the hydrogel has good biocompatibility.The above results illustrate the potential application prospects of the conductive hydrogel in electronic skin,implantable devices,and human motion detection.