Research On Key Technology Of Mass Sensitivity Of Quartz Crystal Microbalance

With the rapid development of science and technology,as the source of information acquisition,the role and status of sensors are becoming more and more important.As a kind of very important mass sensor,quartz crystal microbalance(QCM)has been widely used in many fields.This dissertation takes the key technology of QCM sensor as the research object.Through in-depth study of the sensing mechanism of QCM and combined with finite element method simulation technology,the dissertation reveals the key factors that determine the mass sensitivity of QCM sensor,and puts forward a method to improve the mass sensitivity of QCM sensor by optimizing the electrode structure design.In view of the complexity of theoretical calculation of QCM mass sensitivity of asymmetric electrode configuration,a method based on electrodeposition to measure the mass sensitivity of QCM is proposed,and the three-electrode electrochemical plating experimental platform is established.The mass sensitivity of asymmetric electrode QCM is measured,and it is pointed out that this method can be widely used to measure the mass sensitivity of QCM with other electrode configurations,which means that this method has universal applicability.The main research contents and innovation points in this dissertation are as follows:First,this dissertation has deeply studied the sensing mechanism of QCM.It combined with detailed theoretical derivation,and revealed the relationship between QCM mass sensitivity distribution and the displacement vibration amplitude distribution of the quartz crystal resonator particles.Then,based on the Mason equivalent circuit model and the BVD equivalent circuit model of the quartz crystal resonator,a detailed theoretical derivation of the vibration amplitude of the resonator particle is provided,which provides a theoretical basis for the analysis of the QCM mass sensitivity and its distribution using the finite element method.Second,through the finite element method and combined with Comsol software simulation,the cross-section diagrams of the QCM particle displacement vibration amplitude distribution and the electric potential distribution in the quartz crystal are given.Combined with the relationship between QCM mass sensitivity distribution and particle displacement amplitude distribution,QCM mass sensitivity distribution is analyzed and given.Then,through the simulation analysis of the mass sensitivity distribution of the traditional symmetric electrode QCM and the asymmetric ring electrode QCM,it is found that the mass sensitivity distribution of the ring electrode QCM is more uniform.Third,because the classical Sauerbrey equation does not take into account the effect of QCM electrode materials on its mass sensitivity,it is necessary to study the mass sensitivity of QCM with different electrode materials.By studying and comparing the QCM mass sensitivity of gold electrode and silver electrode,it is found that the gold electrode QCM mass sensitivity is higher than that of silver electrode QCM mass sensitivity,and it is pointed out that the QCM electrode material has an important influence on the mass sensitivity.Then,the effect of electrode thickness on the mass sensitivity of the same electrode material was studied.Fourth,aiming at the complexity of theoretical calculation of QCM mass sensitivity of asymmetric electrode configuration,a method based on electrochemical plating to measure the mass sensitivity of QCM of asymmetric electrode configuration is proposed,and a three-electrode electrochemical plating experimental platform is established.The QCM mass sensitivity of asymmetric electrode configuration is measured,and the surface morphology and surface cleanliness of copper thin films are analyzed by SEM,AFM and XRD techniques.Then,the mass sensitivity of traditional symmetrical electrode QCM is measured by electrochemical plating,and it is pointed out that this method can be used to measure the mass sensitivity of QCM with other electrode configurations,that is,the method of electrochemical plating to measure the mass sensitivity of QCM is generally applicable.