Design And Processing Of Micro Gyroscope Based On The Tunneling Magnetoresistance Detection

Inertial technology is the future development direction,its development depends on the Inertial devices,the micro-gyroscope is the core device in the micro-in Inertial devices.It remains to be an unsolved problem high precision of micro-gyroscope,and the core technology behind micromachined gyroscope is the detection of the Coriolis force.With the miniaturization of MEMS gyroscope,the conventional capacitance detection effect makes the detection resolution limited due to interface circuit resolution,processing technology and parasitic capacitance,making it difficult to achieve high-accuracy detection.Therefore,while developing mainstream detection,we can develop new effects and new principles of micromachined gyroscope research.Tunneling magnetoresistance effect?TMR?is a fourth-generation magnetic sensing technology and its generation mechanism is the spin-dependent tunneling effect.The main advantages of TMR is its high sensitivity,high spatial resolution,small size,and easy detection,and it can overcome the shortcomings of the capacitance detection principle.So we have created the motivation to apply the TMR to the micro-gyroscope to solve the weak Coriolis force detection.The paper designs and fabricates a micro-gyroscope structure based on tunnel magnetoresistance effect,and its sensitivity is planned.The total sensitivity of such TMR gyroscope has four contributions originating from its structure,magnet,the magnetoresistance and amplifying circuit.For the structure sensitivity of the TMR gyroscope,the gyroscope structure is designed and optimized in ANSYS software,and the air damping and thermoelastic damping of the structural are theoretically calcuted.The structural sensitivity of the micro-gyroscope is 10.8 nm/°/s.For the magnetic sensitivity of the TMR gyroscope,a folded-type energized coil that meets the requirements of the detection magnetic field is designed.the energized coil is simulated by Ansoft Maxwell software and is fabricated by Plating process.The change rate of the magnetic field is 3×10^-4 Oe/nm.For the magnetoresistance sensitivity,we test a TMR sensor and the test results show that its sensitivity is 4.26 mV/Oe.For electrical sensitivity,it mainly comes from the amplification of the signal by the detection circuit,and the magnification value is 2000.Based on dynamical equation,a model of the TMR gyroscope system is developed and simulated in the SIMULINK,and the angular rate signal modulation and demodulation is completed.The total sensitivity of the TMR gyroscope is obtained,and the system-level characteristics of the TMR gyroscope are verified.The key parameters of the designed TMR gyroscope are theoretically calculated.The total sensitivity of the TMR gyroscope is 27.6 mV/°/s,and the noise level is0.22°/h.In this paper,the designed TMR gyroscope is fabricated and tested,and the prototype of micro-gyroscope structure and TMR gyroscope are obtained.The TMR gyroscope model prototype is tested partially,including the drive direction tap test and the detection direction tap test,proved that the micro-gyroscope structure is movable and usable.The drive direction resonant frequency of the TMR gyroscope model prototype is 6853 Hz and the quality factor?Q value?is 571.1,the detection direction resonant frequency is 6854 Hz and the quality factor?Q value?is 527.3.Finally,the structural sensitivity of the micro-gyroscope tested is15.3 nm/°/s,which is consistent with the theory.