Design And Test Of Two Dimensional MEMS Magnetic Field Sensor

With the development of smart devices,magnetic field sensors have been widely used in various fields.They expand not only the storage space of the device,but also the realization of high precision positioning and navigation of the transportation equipment such as automobiles,ships,aircraft and even individuals.With the development of society,magnetic sensors are becoming more and more important.They can detect very weak magnetic signals and help people explore unknown fields.At the same time,the development of micro electro mechanical system(MEMS)design and processing technology makes portable magnetic field sensors possible,and intelligence of magnetic sensors is becoming higher.A number of MEMS magnetic field sensors have been developed.So,MEMS magnetic field sensor is introduced in this paper,which can measure not only magnetic field intensity but also the direction of magnetic field.The theoretical model of magnetic field sensor is built and the ANSYS model is simulated,then the sensor is tested and analyzed,and a new design of 3D silicon magnetic field sensor is proposed.In this paper,the magnetic field sensors are tested by a new method.The torsion beam of a magnetic field sensor vibrates in a magnetic field,and the induced electromotive force produced by cutting the magnetic field lines in the magnetic field is measured.The magnitude of the induced electromotive force is proportional to the magnitude of the external magnetic field.By measuring the magnitude of the induction electromotive force,the magnitude of the corresponding magnetic field strength is obtained.At the same time,the magnetic field intensity in different directions is obtained by measuring the induced electromotive force of the cantilever beam with different torsion direction.Because the MEMS magnetic field sensor size is relatively small,leading to the induction voltage of cantilever beam cutting magnetic line generated is relatively weak,the amplifying and filtering circuit are designed to realize signal amplification to improve the detection sensitivity.In addition,the main object of this paper is the torsion beam under resonance,and the theoretical model of the beam is set up from the one-dimensional and two-dimensional torsional structure theory.The frequency characteristic,mode and deformation of the structure are analyzed.The finite element method is used to verify the change of the frequency characteristics of the torsion beam.The relationship between the structure size and the modal,natural frequency and deformation is obtained.The reliability of the simulation is verified by software simulation,and the final error is less than 5%.The research work of this paper also includes sample test,and the final test of the samples with different structures is carried out.The results show that error between the sample result and theoretical result is controlled within 10%.Finally,a new structure for measuring three-dimensional magnetic field is proposed,and its working principle and mode are analyzed.