The Preparation And Properties Of Flexible Multi-functional Electronic Skin Sensors

The electronic skin is a bionic flexible wearable sensor that can obtain the system's perception of various external information by mimicking various sensing functions of the human body.At present,electronic skin has good application prospects in many fields such.as biomimetic devices,intelligent robots,and medical prostheses.However,most of the flexible wearable sensors reported cannot simultaneously have multiple sensing capabilities that can detect various mechanical forces such as pressure,strain and bending or temperature sensitive and photosensitive.Therefore,It has great practical value and guiding significance to explore the sensing mechanism of flexible wearable sensors through the preparation of new materials and the design of new architecture.In this paper,silver nanowires and manganese dioxide nanowires were synthesized and prepared,two different flexible stretchable electronic skin sensors with multiple sensing properties were prepared by structural design,the effects of different nanowire content on the sensing performance of electronic skins were explored,and the electron transfer mechanism of these artificial skin sensors was researched.1)Preparation of silver nanowires(AgNWs)and manganese dioxide nanowires(MNWs)by hydrothermal method,and adjusting the reactant concentration,reaction temperature,reaction time and rotation speed to obtain smaller diameter and ideal length diameter ratio.Then,the physical morphology and crystal structure of the silver nanowires and manganese dioxide nanowires were characterized by various methods such as scanning electron microscopy(SEM),X-ray photoelectron diffraction(XRD)and Raman spectroscopy with good physical morphology and crystal structure.2)The azobenzene and silver nanowires mixed solution was spin-coated on a polydimethylsiloxane(PDMS)substrate by spin coating to form a film,and spin-coated with silk fibroin to prepare a sensing property with ultraviolet light sensitivity.Flexible stretchable biocompatible electronic skin(SF@AgNWs/azobenzene@PDMS e-skin).The electronic skin morphology was characterized by scanning electron microscopy(SEM).It was found that the electronic skin has a three-layer structure with a thickness of at least 150 ?m,and the silver nanowires have a cross-network structure.The electronic skin resistance of the prepared electronic skin was measured by a four-probe method to be 1.3 ?/sq,and the light-emitting diode was allowed to emit light under a direct current of 3V.SF@Ag NW/azobenzene@PDMS electronic skin has excellent mechanical properties(65%breaking strength(EB)and elastic modulus(ME)of 0.87 MPa),can monitor signal changes caused by pressure,bending and 365 nm UV light and show high sensitivity.At the same time,the ultra-thin silk fibroin film provides good biocompatibility.3)The flexible stretchable electronic skin sensor(AgNWs/MNWs@PDMS e-skin)with super capacitive performance was prepared by a mixed solution of manganese dioxide nanowires and silver nanowires spin coated on a polydimethylsiloxane(PDMS)flexible layer and using potassium hydroxide-polyvinyl alcohol as an electrolyte layer.The surface morphology and five-layer structure of the electronic skin were characterized by scanning electron microscopy(SEM).The electrochemical properties of conductive composite films prepared by different manganese dioxide nanowires and silver nanowires were studied,and the optimum concentration ratio was obtained.Through the charge and discharge test(GCD),it was found that the AgNWs/MNWs@PDMS electronic skin sensor has an area specific capacitance of 371 mF cm-2 at a current density of 1 mA cm-2 and good stability after 2000 cycles(The capacitance retention rate is 92.3%and the coulomb efficiency is 94.4%).At the same time,the electronic skin has high sensitivity and stability in detecting mechanical force changes such as pressure,bending and shear.