Research Of Regenerated Silk Fibroin Protein Modified Graphene Aerogel And Supercapacitive Stress Sensor

The construction of flexible and wearable intelligent pressure-sensitive devices has great application potential for human health daily monitoring system,wearable electronic devices and other domains.Compared with the traditional electronic equipment,flexible electronic products have the advantages of convenience,flexibility and high sensitivity,which has great research significance.Currently,carbon-based materials have been widely used in sensor manufacturing due to their excellent electrical conductivity and environmental friendliness.Among them,the stress sensor based on graphene composite aerogel is the current research upsurge.However,the preparation of traditional graphene-based composite aerogels inevitably uses toxic or non-renewable materials.In order to replace non-renewable resources and reduce e-waste disposal,there is an increasing demand for the use of renewable and degradable biopolymers in flexible electronic products.Natural polymers are characterized by light weight,excellent mechanical properties,easy access,non-toxicity,biocompatibility,and low cost.Therefore,it is of great significance to use an environmentally friendly and simple way to fabricate compressible sensor parts and improve their sensing performance,In addition,graphene aerogels have also been widely studied and applied in supercapacitors.These studies provide ideas about us to combine mechanical sensors with supercapacitors.Here,we designed a supercapacitive mechanical sensor based on regenerated silk fibroin protein modified graphene aerogel.The specific content is as follows:（1）The graphene aerogel modified by silk fibroin protein was prepared by high temperature hydrothermal synthesis and freeze-drying method,and the obtained graphene aerogel had regular honeycomb structure.By adding silk fibroin protein,the graphene and silk fibroin protein can avoid the stacking of graphene due to the electrostatic repulsion effect,thus forming a compound aerogel with large volume and low density.In addition,aerogels are much softer,more resilient and more stable.At 50%strain,the maximum return to 100%,and after 500 cycles,still can maintain 90%.By adding silk fibroin protein,the relative resistance of aerogel can be improved and the aerogel has better sense performance and stability.In addition,the sensor based on optimal performance maintains a high mass ratio capacitance of 128.4 F g^-1through three-electrode tests.However,the individual aerogel are light and fragile,and fixing the aerogel directly on the electrode can easily cause the aerogel to break.Therefore,it is necessary to further design a stable and improved performance preparation method.（2）In order to strengthen the aerogel and extend the application of the sensor element,we packaged the aerogel into a simple sensor element and coated it with PVA/H₂SO₄electrolyte.Since the addition of PVA/H₂SO₄electrolyte strengthens the device and provides an internal charge and ion transfer pathway,the sensor device exhibits excellent performance in the voltage capacity,piezo-resistive and piezoelectric response,and exhibits good stability.Within 0.01～10 KPa,the original graphene aerogels sensor capacitance shows a sensitivity of only 0.04 K Pa^-1,and the silk fibroin composite aerogel has the high sensitivity of 0.73 K Pa^-1,which improves the 18 times,and the optimized sensor remaines 87%after 1000 cycles of sensor stability.Finally,through the practical application,it is proved that the device can be used to detect a variety of human movements such as clenched fist and arm swing.It provides ideas about the design of multi-functional wearable supercapacitive stress sensors in the future.