Application Of Electrical And Mechanial Properties Of Black Phosphorene In Flexible Pressure Sensor

With the development of wearable devices,flexible pressure sensors have great application prospects in medical diagnosis,robot manufacturing,electronic skin,and other applications.Flexible capacitive pressure sensors have high sensitivity,simple device structure,and good dynamic response performance.The advantages have been widely concerned by scholars at home and abroad.The great advantages of the new two-dimensional materials in mechanical,thermal,electrical,optical and other characteristics are becoming a new driving force for the industry to leapfrog development.The use of two-dimensional materials as new sensitive component materials is likely to make breakthroughs and get twice the result with half the effort in related fields.Black phosphorene is a new two-dimensional material with atomic thickness after graphene.It is proved that its band gap and material properties are regulated by electricity,force and light.This paper simulates the relationship between the band gap and the dielectric constant of black phosphorene and the strain of the material based on density functional theory.A capacitive flexible pressure sensor was designed and fabricated.The sensor uses PET as a flexible substrate,ITO as an electrode,and black phosphorene/graphene oxide film as a composite dielectric layer.In this paper,the sensitivity,linearity and other properties of the sensor in different pressure ranges are systematically tested.The temperature characteristics,stability and response speed are analyzed,and the performance of this sensor and the performance of the sensor based on the single layer dielectric layer of graphene oxide are compared under different strains.In general,the research content of this paper is mainly divided into the following points:(1)The band gap of black phosphorene and the variation of dielectric constant under material deformation were simulated by CASTEP module of Materials Studio software.The simulation results show that the band gap of black phosphorene decreases with strain increases.When the compressive strain in the direction of armchair is greater than 13%,the black phosphorene is converted from a semiconductor to a conductor;at the same time,the dielectric constant of the black phosphorene increases as the strain increases.Since the dielectric constant of black phosphorene can be controlled by strain,a dielectric layer in which black phosphorene and graphene oxide are layered is creatively proposed,and the equivalent dielectric constant model of the layered composite dielectric layer is analyzed.(2)A capacitive pressure sensor based on black phosphorene and graphene oxide composite dielectric layer was prepared by experiments,and the performance of the sensor was tested and analyzed.The capacitance change of the sensor conforms to the parallel plate capacitance model,and the capacitance output is mainly affected by the plate spacing and the effective dielectric constant.The sensor has a sensitivity of 1.28 kPa~-11 in the range of0-2.5 kPa,and also has good linearity,small temperature drift,high stability,short response time(less than 300 ms),and large range(0-25.0 kPa),etc.(3)Comparing the output performance of capacitive pressure sensors based on pure graphene oxide and composite dielectric layers under different strains,theoretical studies show that the larger the deformation,the larger the dielectric constant of black phosphorene,and the larger effective dielectric layer of the composite dielectric layer,so the change rate of the output capacitance of the sensor based on the composite dielectric layer is significantly greater than the change rate of the output capacitance of the sensor based on the pure graphene oxide dielectric layer.The experimental results also confirm this point.Experiments have shown that black phosphorene used as dielectric layer has feasibility and superiority.(4)Applying the pressure sensor to limb monitoring,the test results show that the capacitive pressure sensor based on the black phosphorene and graphene oxide composite dielectric layer can sensitively detect different actions of the human body,and the output capacitance is stable.It is less volatile and is expected to be used in areas such as electronic skin and wearable devices.According to the above research,black phosphorene can be used as a dielectric material in flexible capacitive pressure sensor,and the prepared pressure sensor has excellent performance and has great application prospects in the wearable field.