Study On The Viscosity Measurement Of Liquid Based On Double-Resonator

Viscosity is an important parameter that directly reflects the characteristics of liquid,and viscosity is widely used in medicine,petroleum,chemical,textile and other industries.In this paper,the principle of the traditional method for measuring viscosity is analyzed and its deficiency is pointed out.Then the method of measuring viscosity by QCM is proposed.Quartz crystal microbalance(QCM)is a new type of sensor.The traditional QCM uses thickness field excitation mode that the electrodes are located on both sides of the quartz crystal,and once QCM works in the liquid phase,the electrodes will be corroded by the liquid.However,the QCM of lateral field excitation mode that the electrodes are located on the same side of the quartz crystal does not contact the measured liquid directly,thereby QCM's service life is prolonged.The physical properties and basic working principles of quartz crystal are elaborated in detail.The mechanism of QCM for detecting trace mass is explained by the equation of QCM mass effection,and the QCM resonance frequency is affected by viscosity and density of the measured liquid in liquid phase.Based on Sauerbrey and Kanazawa-Gordon equations,the feasibility of using a dual-resonator to detect viscosity of liquid was determined.In this paper,a double-resonator structure(QCM-A and QCM-B)is designed to detect the viscosity of the liquid.The electrode structure of QCM-A and QCM-B is the same,but the QCM-A sensing surface is smooth,and the QCM-B sensing surface is engraved with micro-grooves.Regarding the size design of the micro-grooves on the QCM-B,ANSYS Workbench and Workbench Acoustic Extension acoustic plugin are used to simulate QCM-B theoretically.For different size micro-grooves of QCM-B,ANSYS calculates the resonant frequency of QCM-B in air and in the viscous liquid to optimize the size of the micro-grooves.The dual-resonator chip is processed by combining the results of finite element analysis and MEMS micromachining technology.Considering the application of the dual-resonator,a three-layer flow cell structure is designed for loading the dual-resonator chip.The designed double-resonator was used to test the viscosity of the liquid.According to the experimental data,the relationship between the sensitivity of the double-resonator to detect the viscosity and the size of micro-grooves on the QCM-B was obtained.And the reliability of detecting the viscosity of the liquid based on the double-resonator was verified.