Patterned Electrodes On Protein Based Substrates For Energy Storage And Wireless Sensor Devices

The demand of flexible wearable electronic devices has been continuously increasing,it is of great significance to reduce the generation of "electronic waste",and to realize the flexible energy supply and wireless signal acquisition of flexible electronic devices.Regenerated silk fibroin is a natural biological protein,with good biocompatibility to human body and degradability.However,the film fabricated by pure regenerated silk fibroin(RSF)protein,is naturally stiff and brittle,and easily resolves in aqueous solution,which limits its application in the field of flexible electronics.In this thesis,polyurethane(PU)was incorporated into the RSF solution to prepare a flexible regenerated silk fibroin composite membrane(RSF/PU membrane).Then,the patterned electrodes fabricated by inkjet printing method on this substrate,are applied in micro-supercapacitors and LC wireless passive sensors.The main contents and achievements of the thesis are as follows:1.The RSF protein was extracted from silkworm cocoons,and then some polyurethane was added to the RSF protein solution for modification.A rough RSF/PU membrane was prepared by a solution casting method.The incorporation of polyurethane is beneficial to promote silk fibroin from random coil to the stable ?sheets secondary structure,promoting the water insoluble ability of the composite membrane.In addition,compared with the pure RSF membrane,the thermal stability of the RSF/PU membrane is greatly improved,and its tensile strength is increased by 5 times,indicating that it can be a good choice for flexible electronic substrate.2.MnO2@Ni@Ag and PPy@Ni@Ag interdigitated finger electrodes were respectively prepared on the surface of the RSF/PU membrane by inkjet printing and electrochemical deposition.The optimal deposition time of the electrode,and the performance of symmetric flexible solid-state micro-supercapacitor based on the electrode were investigated.The device of the MnO2 electrode,with a capacitance of 10 mF cm-2 at the scanning rate of 10 mV/s,a retention rate of 89.97%after 5000 cycles of charge and discharge tests,and a retention rate of 92.8%after 2000 bending tests,shows its good flexibility and stability.The device based on the PPy electrode,provided a capacitance of 49.34 mF cm-2 at a current density of 0.2 mA cm-2,and a maximum energy density of 4.39 ?Wh cm-2.3.The Cu@Ag spiral coil electrode(ie,inductor L)was prepared on the surface of the RSF/PU membrane by inkjet printing and electrochemical deposition.The LC wireless passive flexible pressure sensor,which was assembled by the capacitive pressure sensor and the inductor,has a sensitivity of 0.9207 kPa-1 at low pressure range(0-15 kPa),while achieves a sensitivity of 0.0213 kPa-1 at high pressure range(120-348 kPa).The device has good stability and can be used for monitoring human activities,showing its application prospects as an implantable wireless monitoring flexible electronic skin.