| The aviation,aerospace,marine and other fields put forward the urgent need for high-precision pressure sensors.The new pressure-sensitive material-graphene has been widely used in the development of pressure sensors because of its excellent mechanical and electrical properties.At present,high-precision graphene pressure sensor prototypes have been manufactured.From the current testing results of graphene pressure sensors,the initial section of the pressure change is not sensitive and the results are random,reducing the Linearity and accuracy of the pressure sensors.At the same time the graphene membrane suspended in the cavity is prone to be broken in the processing,resulting in a low sensor yield.Therefore,the hexagonal boron nitride(h-BN)material with similar properties to graphene has been introduced and the piezoresistive effect of the graphene/h-BN heterostructure membrane has been studied,and then the graphene/h-BN heterostructures of the pressure sensor design methods and manufacturing process,and the prototype of the packaging have been explored.And the testing results have been analysized.The main contents of the thesis include:1.Graphene/h-BN heterostructure membrane piezoresistive effect modeling and sensor sensitivity modelingIn order to find out the specific working mechanism of the graphene/h-BN heterostructure pressure sensor and provide the model guidance for the subsequent pressure sensor design,the piezoresistive effect and the quantitative relationship between membrane size and sensor sensitivity has been studied.Firstly,the finite element simulation methods and the mechanical analysis methods have been used to study the relationship between pressure and strain in the piezoresistive effect of graphene/h-BN heterostructure membrane.The finite element simulation model and theoretical models has been established for the relationship between pressure and strain.Secondly,the relationship between strain and resistance in the piezoresistive effect of graphene/h-BN heterostructure membrane have been studied by using the theory of molecular dynamics.The strain coefficients GF,which characterize the relationship between strain and resistance,have been calculated.Furthermore,the quantitative relationship between the size of the heterostructure membrane of the graphene/h-BN heterostructure pressure sensor and the sensor sensitivity has been studied by combining the results of pressure-strain and strain-resistance modeling.These models can guide the design of graphene/h-BN heterostructures membrane size of pressure sensor.2.Graphene/h-BN heterostructure pressure sensor design and manufacturing methodsAiming at the present situation that the design and process of the graphene/h-BN heterostructure pressure sensor are not yet clear,the design and manufacturing methods of the pressure sensor have been explored.The size of the pressure sensor has been designed according to the results of the piezoresistive effect of the graphene/h-BN heterostructure membrane and the results of the membrane size-sensor sensitivity modeling.The process technology and processing parameters of the sensor have been designed by using the current microelectromechanical system manufacturing technology.The processing technology of the heterostructure thin film heterogeneous structure sensor of graphene/h-BN has been studied and the effect of the main processing technology has been observed and evaluated.The graphene/h-BN membrane has been characterized in the processing through the optical microscope,the scanning electron microscope and the Raman spectrometer.3.Graphene/h-BN heterostructure pressure sensor packaging and testingThe graphene/h-BN heterostructure pressure sensor is encapsulated and tested,and the test results have been analyzed in depth.Firstly,the pressure sensor has been packaged according to size and structure.Secondly,the testing platform has been established according to the pressure sensor test program and the graphene/h-BN heterostructure pressure sensor has been tested by changing the environment pressure.Finally,the factors that affect the performance of the sensor during the manufacturing and testing process have been analyzed to provide guidance for further improving the performance of the graphene/h-BN heterostructure pressure sensor... |
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