Design Of Micro Cantilever Sensitive Structure Based On MEMS Technology

Micro Electro Mechanical Systems(MEMS)is composed with micro-sensors,micro-actuators,micro-signal processing and control circuits that meet specific requirements,but not simply miniaturizing macro-machinery,so that make it an intelligent micro-function unit to form an intelligent micro system.MEMS micro-cantilever sensors feature of high sensitivity,fast response,miniaturization and real-time measurement,they are widely used in the fields of chemical,physical and biological measurements.In the current integrated applications,the MEMS micro-cantilever sensors mostly work in the static mode,the signal-to-noise ratio is relatively low,they are easily affected by the environment,affecting the accuracy of their detection signals.The working mode of dynamic detection mode has strong anti-interference ability and fast detection speed,which is more suitable for integrated,miniaturized and real-time applications.In view of the above problems in integrated applications,this paper adopts a dynamic working mode with strong anti-interference ability and fast detection speed,combined with the characteristics of new nano-composites,this paper designed that a micro-cantilever structure sensor with self-driving and self-sensing function.Based on the simple and easy-to-integrate piezoelectric drive method,and signal detection circuit is simple,easy to prepare,piezoresistive detection method that can be used for complex environment measurement.a nested layout step-by-step micro-cantilever sensor-sensitive structure is proposed based on the elasticity theory of multilayer micro-cantilever structure to realize self-driven and self-sensing functions.At the same time ensure the sensitivity and mechanical response of the sensor.Based on the piezoelectric equations of the inverse piezoelectric effect,using the COMSOL software to establish the piezoelectric driving model,it is studied the influence of the PZT piezoelectric layer structure parameters on the performance of the micro-beam sensor.Based on the varistor output potential difference equation of the piezoresistive effect,a piezoresistive detection model was established,and it was studied the influence of the force sensitive resistance parameters of the piezoresistive layer on the output characteristics;The integrated model of the micro beam sensor was established by integrating the piezoelectric driving layer and the piezoresistive detection layer model,and the size and performance parameters of the micro beam sensor sensitive structure were obtained.The multilayer nanomembranecomposite micro-cantilever sensitive structure sensor designed in this paper has a sensitivity of624.5mV/MPa,a zero output potential difference of 0.05 mV,a resonant frequency of 420 kHz to 480 kHz,a typical value of 446 kHz,and a maximum load pressure of 200 kPa,and a critical load factor of-5.72,the maximum stress of the micro-cantilever sensitive structure is 2.97 GPa.Finally,according to the optimized design scheme,based on the MEMS technology,combined with LPCVD and "sol-gel" method,the preparation of micro-beam structure sensor is proposed.The micro-cantilever structure and its preparation scheme proposed in this paper use the excellent mechanical properties of the polysilicon film to improve the stability of the multilayer composite structure,as to promote intelligent,integrated application of precision sensor technology development on the basis of ensuring the detection sensitivity,the degree of integration of the cantilever beam sensor is improved,which lays a foundation for the commercialization of portable detection instruments,wearable medical equipment,and intelligent precision sensors.