Preparation Of Transient Electronic Devices With Silk Fibroin Film As A Flexible Substrate

Traditional electronic products are given priority to with rigid components,excellent performance at the same time it still has limitations,cannot adapt to the uneven working plane.In recent years,the emergence of flexible electronics has provided a new development direction for electronics.As a new member of wearable devices,it is widely used in wireless communication,image display,motion sensing,biomedicine,energy supply and other fields.The construction method of the flexible device is mainly to form a functional pattern array on the surface of the flexible substrate by means of screen printing or 3D printing of conductive substrates such as metal nanoparticles,carbon-based conductive materials or conductive polymers.On this basis,choosing the appropriate substrate material can give the device a characteristic of controlled degradation,reduce the accumulation of waste electronics,improve the safety when used for information storage,and avoid the risk of secondary surgery as an implantable medical device.In this study,silk fibroin films with good biocompatibility and controllable degradation were used as substrate materials for flexible transient devices.Three schemes were adopted to improve the brittleness of silk fibroin films and increase the elongation at break of the films.First of all,polysaccharides are a class of natural biodegradable organic polymer materials with wide sources and low cost.Considering that polysaccharides are rich in hydroxyl,carboxyl and amino groups,we attempted to prepare fibroin proteoglycan composite films with good flexibility by using the molecular interaction between polysaccharides and silk fibroin.The experimental results showed that the silk fibroin chitosan composite film cross-linked with glutaraldehyde had a breaking elongation of up to 20%,which was significantly improved compared to the single component silk fibroin film.Secondly,the influence of film brittleness was improved by regulating the thickness of silk fibroin film.The test results showed that as the thickness of the silk fibroin film decreased,the elongation at break and tensile strength of silk films increased gradually.The elongation at break of silk fibroin film with a thickness of 90 ?m was as high as 11.2%,and the tensile strength of the film was 82.47 MPa.Finally,we used glycerin as a plasticizer to improve the flexibility of the film.In order to suppress the loss of water solubility of the silk fibroin film by glycerol,we introduced calcium salts,using the metal complex between the calcium ion and the silk fibroin peptide chain and the ability of calcium salts to bind water molecules,reducing the crystallinity of the film,further improved the elongation at break of the film,up to 500%,so that the film can disintegrate instantly in water.The prepared blended film of calcium silk fibroin and glycerin had good insulation properties.The introduction of calcium salt also gave the film a strong adhesion performance,and the adhesion strength can reach to 42 MPa,which further proved that silk fibroin film had great application prospects in the construction of flexible transient devices.