Study On Static And Dynamic Noise Model Of Electrochemical Seismic Sensor

As one kind of important sensor which is widely used in fields of seismologic measurement and geography, acceleration sensors are significant in the market. Among all types of acceleration sensors, acceleration sensors equipped with solid-mass inertial element occupy a high proportion. However, for low-frequency or ultralow frequency signal measurement applications, acceleration sensors with solid-mass inertial element are limited by more complex structure, low resistance to interference,higher cost and other shortcomings. Compared with the acceleration sensors equipped with solid-mass inertial element, a novel micro-channel electrochemical sensor(Micro-flow Electrochemical Sensor, MES) with electrolytic solution as the liquid-mass inertial element achieves a better performance in the field of low frequency range.In this thesis, the noise characteristics of electrochemical seismic sensor will be studied. In the view of the noise origin, static noise and dynamic noise will be classified. In order to deduct the influence of the noise and improve the SNR(Signal Noise Ratio), these two types of noise will be the kernel study in this thesis as follow:(1) Face to the complex process of electrochemistry and electronics, effective output signal and noise should be decoupled. Due to the final target of studying the noise of the sensor, this complex process of electrochemistry should be abstracted as a correct equivalent circuit model to decouple the output signal out of the noise. With the proposed equivalent circuit model, the specific parameters of sensor can be connected with the parameters in circuit model.(2) Complete the analysis of static noise model. According to the combination of fluid flow dynamic model and natural convection thermal noise model, sensing element of the sensor is studied. With the single channel model in the sensing element, distribution of velocity magnitude can be observed and as a result, the static noise derived by natural convection corresponds to the geometry of the single-channel’s section. By comparing with the shape of the single channel, a new noise deduction method is presented.(3) Complete the analysis of dynamic noise model. Besides the study of static noise, the type of dynamic noise caused by electrolyte striking the sensing element is also studied in this thesis. When the electrolyte moves with the acceleration signal, it will shock the part which is the conjunction of the multi-channel structure. The result of the influence above will cause the inlet/outlet effect which derives the turbulence-laminar noise. With the numerical and practical experiments in this thesis, methods dealing with this type of noise is presented. Finally, the elastic membrane element is also discussed in this part and the dynamic character effected by the noise is also analyzed.