Research On The Resonant Level Of The Liquid Sensor

Resonant quartz crystal sensors are widely used in various fields of science andtechnology. Resonant quartz crystal sensors has many advantages, such as, highsensitivity, high precision, simple structure, long using life, low power consumption,high environmental adaptability, etc. It is a low-cost sensing devices. Piezoelectricquartz crystal sensors are widely used in gas, liquid analysis and the analysis of thespecial liquid, penetrate into many areas, such as, the surface chemistry, appliedchemistry, biochemistry, microbiology and other areas as element detection. QCM(Quartz Crystal Microbalance) is based on the changes of the quality touching thequartz crystal surface, using the inverse piezoelectric effect to make the mass changesconverted into frequency characteristic’s changes, so as to achieve the detection of gasor liquid. The design of quartz resonator mass-sensitive sensor electrode has a greatimpact on parameters on the performance of the sensor and the resonant frequency ofthe crystal that detected, so it is very important to design the size of the electrode inorder to achieve a specific function.In this paper, the research direction is quartz crystal liquid level sensor. Thealuminum deposition was deposed on the surface of quartz crystal using the vacuumcoating methods. Quartz crystal frequency vibration modes was analyzed by theprinciple of quartz crystal microbalance. Mathematical model analysis and equivalentcircuit model analysis was made. Through the analysis of the mathematical model of thesensor, we know the relation between the frequency and liquid density, viscosity, quality.It provided a firmly theoretical foundation in the design and fabrication of quartz fluidlevel sensor.This paper studied on quartz crystal sensor technology and the design of electrodestructure. Before the vapor deposition, using software to design the shape of vapordeposition. The line of the mask was drew by machining. The electrode of the quartzcrystal was made by using the processed mask. In the process of vapor deposition,different thickness of the films were deposed in the range of the melting point of thealuminum by using the resistance wire heating mode. The electrodes were designedthree shapes of round, square, oval. Analyze the frequency characteristic of quartzcrystal sensor that had electrodes with different shapes in order to have the optimalelectrode. Set up a comparison test mainly for the difference in the radius, thickness,shape of the electronic. Different viscosity and density of the liquid was measured. Thefilm surface morphology that deposes by vacuum vapor deposition was analyzed.