Research On Nonlinear Dynamics Characteristics Of Micro-resonant Sensors

As an important part of microelectromechanical systems,silicon microresonance sensors have the advantages of small size,high accuracy,easy integration with detection circuits,fast response,and difficult to distort frequency signals,and have broad market prospects.In this paper,the nonlinear and chaotic vibration characteristics of micro resonant sensors are studied.Low,medium and high frequency detection circuits are designed and developed.Sensor fabrication and related detection experiments are completed.Based on the large deflection theory of the film and the theory of continuous system vibration,a multi-field coupled nonlinear dynamics equation of the film pressure sensor is proposed.The nonlinear natural frequency,near-resonance and far-resonance time-domain dynamic response equations are obtained.The influence of system parameters on nonlinear natural frequency,amplitude-frequency characteristics when approaching resonance,and dynamic response in time domain away from resonance are revealed.The results show that when the initial gap is below 400 nm,the molecular force should be considered in the micro resonant pressure sensor system.Multi-field coupled nonlinearity can change the natural frequency and dynamic response of the sensor.A multi-field coupled nonlinear dynamic model of a cantilever resonator for a micro-resonant gas sensor is established,and the system nonlinear natural frequency,amplitude-frequency characteristic curve,and dynamic response equation in the time domain away from resonance are obtained.The influence of system parameters on the natural frequency for the system,the amplitude-frequency characteristics close to resonance,and the dynamic response in the time domain far from resonance are analyzed.The results show that the multi-field coupled nonlinearity causes the natural frequency and vibration response of the system to change.When the resonator gap is less than 500 nm and the length is greater than 1 mm,the influence of molecular force on the natural frequency and dynamic response of the micro sensor becomes significant.The multi-field coupled chaotic vibration characteristics of the thin-film micro resonant pressure sensor are analyzed.The time-domain diagram,phase diagram,Poincaré cross-section diagram and frequency spectrum diagram are used to reveal that the way of the resonant system from periodic vibration to chaotic vibration is the period-doubling bifurcation.The proportional-derivative control method is used to control and analyze the chaotic vibration caused by various influencing factors of the sensor.It is found that the chaotic vibration of the sensor will be caused when the parameter selection is inappropriate;the chaotic vibration state of the sensor can be effectively controlled by the proportional differential control method.The multi-field coupled chaotic vibration characteristics of cantilever micro resonant gas sensor are studied,and the influence of system factors on the chaotic vibrations is analyzed.The influence of related parameters on the chaotic vibration during gas detection is revealed.The control and analysis of the chaotic vibration of the sensor are carried out using the proportional differential control method.The study finds that when the sensor is in a stable periodic vibration phase,the harmonic oscillator may also be transformed into chaotic vibration during gas detection.The thin-film micro-resonant pressure sensor,cantilever-type micro-resonant gas sensor,and micro-resonant biosensor are designed and developed using micro-machining technology.Using closed-loop feedback methods,the equivalent mass of the sensor resonator is reduced and the resoant frequency of the sensor is increased.A low-frequency detection system,an intermediate-frequency detection system,and a high-frequency feedback detection system based on a phase-locked loop are designed.The pressure sensitivity experiment of the pressure sensor,mid-low frequency gas sensitivity experiment of the gas sensor,and oxygen absorption / deoxygenation high-frequency detection experiment of the biosensor are completed.The mass of a single oxygen molecule is measured.It is found that when 180 ° feedback is added,the sensitivity of the resonance sensor is greatly improved,which verifies the feasibility of the designed high-frequency detection circuit in the field of biochemical sensors.