Design And Optimization Of Three-axis Capacitive MEMS Micro-accelerometer

Micro Electro Mechanical Systems（MEMS）is a cutting-edge research field involving electronics,mechanics,physics,biomedicine,and other disciplines and technologies.MEMS sensors are widely used in aerospace,medical equipment,automotive electronics,intelligent terminals,and other fields due to their advantages of miniaturization,low cost,low power consumption,high integration,and intelligence.MEMS micro accelerometers are one of the key research directions of MEMS sensors,and are widely favored in the fields of inertial navigation,vehicle safety,and mobile devices.Based on Newton’s second law,this thesis focuses on the mechanism research of capacitive micro accelerometers,analyzes the key performance indicators of micro accelerometers,proposes feasible structural design schemes,and conducts structural modeling and simulation analysis with the aid of ANSYS software.The specific research contents are as follows:Aiming at the range performance and structural stability,a high-range three-axis capacitive micro-accelerometer was designed.The L-shaped elastic beam and differential capacitance structure were selected to model and simulate the designed micro accelerometer.Explore the impact of the parameter size of the key component elastic beam on the performance of the micro accelerometer,and determine the parameters of the elastic beam.Through structural statics simulation,the displacement sensitivities in the X,Y,and Z axes are respectively 4.27×10^-5μm/g,3.12×10^-5μm/g and 1.07×10^-4μm/g.The measuring ranges in the horizontal direction and the Z axis are±1000g and±500g,respectively,and have good linearity in each axis.It can withstand an acceleration impact of 20000g in the X and Y axes,and 5000g in the Z axis,with high overload resistance.Finally,the natural frequencies and vibration modes of the micro accelerometer in three axes were obtained through structural dynamics modal analysis,and the results were consistent with the harmonic response analysis.In order to improve sensitivity performance,a high-precision±100g triaxial capacitive micro-accelerometer was optimized and designed.Select a serpentine beam with a small stiffness coefficient,reasonably design the differential capacitance,and appropriately increase the number of comb electrodes.The displacement sensitivities of X,Y,and Z axes obtained from static simulation are 5.11×10^-4um/g,5.08×10^-4um/g and3.61×10^-4um/g.The measuring range in three axial directions is±100g,which can withstand the impact of 2000g acceleration,and has a good linearity performance.Through structural dynamics simulation,the order of magnitude of each axial resonance frequency is within ten kilohertz,meeting the design requirements.