Study Of Signal Processing Method Used In Thick Film Capacitive Micro-displacement Sensor

In order to in-depth study the force and motion state of the object in micro-nano environment, to realize the measurement of force and displacement in nano-scale, to establish related theory and method, to sense the force and position and to create condition for real time visualizing observation of PZT driven platform, an novel high precision thick film capacitive micro displacement sensor had been studied and designed using thick film technology in this thesis.In order to in-depth study the force and motion state of the object in micro-nano environment, to realize the measurement of force and displacement in nano-scale, to establish related theory and method, to sense the force and position and to create condition for real time visualizing observation of PZT driven platform, This paper presented the design,preparation and testing methods of micro displacement sensor which is coped with the micro-nano enviroment,and developed a novel high precision thick film capacitive micro displacement sensor using thick film technology.Considering the use occasion of PZT displacement detection, we adopted a periphery fixed structure for the capacitor in this thesis. Combined with thick film screen printing,sintering,and integrated technology to develop the research of structure and prepartion process about displacement capacitance sensor.Experiments show that when the capacitor plate gap correct to 20μm <δ0< 75μm,the capacitance of reference capacitors and measurement capacitors are about 50pF, linearity and sensitivity characteristics of the sensor can be balanced at this point.A chief disposal circuit consist of CAV414 is designed to receive the signal of the capacitor sensor, we use needle to connect the sensor and the circuit, which is convenient for miniaturization.Thick-film capacitive sensor and the whole detect system with processing circuit were calibrated respectively. Experiments show that the ring structure of the electrode for compensation of the thick film capacitive sensor has good stability, high precision, long-term and good reliability, strong anti-interference ability, drift coefficient,etc; CAV414 as the core of signal processing circuit, using the high-precision resistors (0.1%) and NP0 capacitors instead of an external common resistor and capacitor elements, the output voltage stability and temperature drift characteristics are significantly improved; after the processing of circuit, nonlinear characteristics of thick-film capacitive sensor is greatly increased.Calibrationing thick-film capacitance sensor in the range of 0-20kPa,we found that a linearity of 3% of the capacitive sensor disposed with the processing circuit, the output voltage signal is reduced to 1%.The thick-film capacitive micro-displacement sensor designed in this paper has many advantages like the simple structure, low cost, easy for miniaturization and product. It is suitable for PZT-based three-dimensional moving platform and the mechanical and electrical control system, provides scientific methods and technique for the robot operation Real-time observation in the nano-environment, meanwhile the results of this study can be applied to other fields. Implementing the real time sensing of Nanometer displacement offers technique support for the development of micro electric mechanical systems(MEMS), micro-machining, and micro-manufacturing and relative fields.