Study On The Influence Of Temperature And Machining Error On The Dynamic Of Comb-Drive Resonators

The rapid development of MEMS technology has brought huge impact to the human production and the progress of science and technology.As one of the most important MEMS devices,micro-resonator provides many new methods for precision measurement,and creates opportunity for studying a variety of physical phenomena.Micro-resonator is one kind of typical Micro-electro-mechanical devices which has been widely used in various fields like air test,automobile and medical test,it not only can complete the complex mutual transformation between mechanical energy and other energy but also has advantages such as flexible design,simple structure and can produce larger vibration amplitude.Therefore,micro-resonator becomes one of the hot spots in the process of the MEMS research.Micro-resonator vibrates along the driving direction,the corresponding natural frequency of the working mode is its resonant frequency.Resonant frequency and quality factor is the two most important and the most basic parameters when designing micro-resonator,resonant frequency determines the applications of micro-resonator.Parameters of micro-resonator like machining error of comb fingers,the prestress caused by dc bias voltage,the change of various structural parameters and temperature stress will influence resonant frequency of the structure and order of the the driving mode.Reveal such influence fully is of great significance to the design of structure and performance of ascension.This paper addresses the influence of these parameters with comprehensive and detailed analysis.Establish the finite element model of micro-resonator with the finite element software ANSYS,and study the influence caused by side error of the movable fingers,the initial overlap length,dc bias voltage on distribution of electric field,it turns out that side error of the movable fingers has evident influence on corner effect and fringe effect of electrostatic field.Load the electrostatic force caused by dc bias voltage to micro-resonator to obtain prestress,study the influence caused by side error of the movable fingers and the initial overlap length on resonant frequency and the driving mode,it is found that side error of the movable fingers has no influence on resonant frequency of micro-resonator,but will affect its first order natural frequency which can work for torsion.Study the influence caused by the length of the supported beam,the length and number of comb fingers on mechanical property of micro-resonator.The Analysis tells that the length of the supported beam and comb fingers have effect on the order of driving mode and the resonant frequency of the micro-resonator,however,the number of comb fingers just affect the resonant frequency,resonant frequency can be implemented by changing the number of comb fingers,resonant frequency is influenced obviously by the length of supported beam.The change of environment temperature can affect the force caused by air damping andthermoelastic damping of the structure on micro-resonator,and the temperature stress will cause stiffness of micro-resonator to change,then affect the accuracy of micro device and the stability of the system.Thermoelastic damping of micro-resonator is from energy dissipation in the process of movement.Thermoelastic damping is the inherent way of energy dissipation of system.Establish a quarter of the mechanical model of micro-resonator according to the symmetrical structure.Deduce the calculation formula of the equivalent thermal elastic damping coefficient of micro-resonator,obtain resonant frequency of micro-resonator and natural frequency of micro beam at different temperature by combining with finite element method,study the resonant frequency and quality factor at different temperature conditions further.Find that the air damping and thermal elastic damping have great influence on resonant frequency and quality factor of micro-resonator,when temperature rises,resonant frequency and quality factor will decrease accordingly.The study provides theoretical basis for temperature compensation of micro-resonator,and provides the basis for the study of the effect caused by thermoelastic damping on mechanical property of micro-resonator.