| With the advantages of small size, high sensitivity, good stability, little temperature drift,low power consumption and working well in the force balance model, etc., MEMS capacitiveinertial sensor has been widely used in military affairs, automotive industrial, biomedicine,consumer electronics, inertial navigation and other fields.First, the measurement and control principle and system dynamic model of the capacitiveinertial sensor are introduced in this paper. And on this basis, a novel micro-inertial sensorembedded horizontally movable electrodes is designed by three aspects, which are supportingbeam, micro-actuator and detecting capancitance, respectively. Through analysis and contrast todifferent structure models, U-shape beam structure, electromagnetic actuator and comb-gridcapacitance structure are chosen in the design. In order to depress the limitation of DRIE (DeepReactive Ion Etching) on high aspect ratio and reduce the noise, an actuator is designed in thepaper and the working principle of electromagnetic actuator which can significantly increase theinitial capacitance is introduced particularly. Through embedded horizontally movable electrodesand the force produced by electromagnetic actuator, capacitance gap is reduced to 0. The resultsshow that initial capacitance is increased to 6.4pf from 1.28pf.According to the above theory analysis and parameter design, the whole structure model ofthe novel capacitive micro-inertial sensor is given, which is simulated is by the finite elementanalysis software Ansys. Results show that the stiffness of supporting beam is large innon-sensitive direction, which greatly inhibits the axial-cross effect. The static displacementsensitivitiy of sensor is 0.659μm / gand the capacitive sensitivities before and afterelectromagnetic actuator is applied are 0.15pf/g and 0.192pf/g, respectively, which is 1.28 timesof the original. At the same time, the stress analysis shows that the sensor can sustain accelerationof 1000g and not be damaged. Then by using the electromagnetic analysis softwareANSOFT-Maxwell, the effects of fringe effect to the sensor performance are analyzed, whichshows that for the small sized capacitive sensor, fringe effect can not be ignored.The territory of the micro-inertial sensor and the manufacturing processes of MEMS deviceare designed. And the designed sensor was manufactured. At the same time, through the crosssection of sensor, the internal units and detection capacitor are showed and real working principleis also given. All of those can prove the feasibility and rationation.The interface detection circuit of micro-inertial sensor is proposed and theoretical analysisand explanation are given. Then the simulation of the designed detecting circuit is analyzed using software Pspice and the experiment results are tested. |
