Research On The Sensitivity Of QCM Sensor And Its Application In Blood Coagulation

Quartz Crystal Microbalance(QCM)is a resonant sensor based on the piezoelectric effect of quartz crystal,which can convert changes in mass,liquid density viscosity,and liquid electrical properties(dielectric and conductive)into changes in its own resonant frequency.The emergence of QCM provides a new high-precision detection method for the fields of physics,biomedicine,chemistry,etc.For example,QCM’s sensitivity to liquid viscosity density,conductivity and dielectric provides the possibility for simultaneous detection of blood and coagulation.And the QCM’s advantages such as real-time detection and simple structure of the detection system make it an optional solution for hand-held coagulation instruments.This dissertation focuses on the current QCM problems such as uneven distribution of mass sensitivity,unclear sensitivity distribution of liquid viscosity density,and unclear response characteristics of QCM to the electrical properties of liquids.The relationship between mass sensitivity distribution and electrode was studied theoretically and experimentally,the sensitivity distribution of liquid viscosity density was measured experimentally,the response characteristics of QCM to the electrical properties of liquid and the factors affecting the sensitivity were studied experimentally,and the application of QCM with "n-m" type electrode in blood and coagulation was investigated based on the sensitivity of QCM to liquid viscosity density and electrical properties.The main contributions of this dissertation are as follows:First,the mass sensitivity distributions of the "n-m" type electrode,dot-multiring electrode,and ring electrode QCM were analyzed.(1)The influence of electrode diameter and thickness on the mass sensitivity distribution of the "n-m" electrode of QCM were analyzed by theory,finite element simulation and experiment,and the relationship between the electrode thickness,diameter and mass sensitivity was revealed.(2)The relationship between the mass sensitivity distribution of dot-multiring electrode QCM and the electrode diameter and thickness were analyzed by theory and finite element simulation,and a method to improve the mass sensitivity distribution uniformity of the dot-multiring electrode QCM is given.(3)The mass sensitivity distribution of ring electrode QCM was analyzed theoretically and experimentally,and the condition for achieving uniform mass sensitivity distribution under silver electrode material is given.Second,theoretical analysis of the classical model of QCM in liquid phase reveals that the mechanism of QCM sensitivity to liquid viscosity density lies in the vibration of the quartz crystal coupling with the liquid at the QCM surface;therefore,the non-uniform vibration intensity distribution may have an effect.Then,the sensitivity of QCM to liquid viscosity density and its influencing factors were analyzed experimentally through the "nm" type electrode QCM,and the relationship between the sensitivity and the liquid coverage area and location was revealed,and the shape of the sensitivity distribution was given.Third,based on the "n-m" type electrode,the response characteristics and sensitivity of QCM to the electrical properties(dielectric and conductive)of liquids were experimentally analyzed by different electrode diameters and fundamental frequency.The results reveal the relationship between the QCM frequency change and the dielectric constant of the liquid,as well as the coupling relationship between the conductive and dielectric properties of the liquid,and the factors affecting the sensitivity are obtained.Fourth,the application of "n-m" electrode QCM in the detection of different concentrations of plasma and coagulation was experimentally studied.The experimental results revealed the relationship between QCM frequency change and plasma concentration;QCM frequency change can well reflect the coagulation process.The results validate the feasibility of the "n-m" electrode QCM to detect plasma concentration and coagulation process.In summary,the sensitivity characteristics of QCM to mass,liquid viscosity density,liquid dielectric and conductive properties,and the influence of electrode on the sensitivity were thoroughly analyzed.And the "n-m" type electrode QCM was applied in the detection of blood and coagulation.The research results can provide some reference for the design of QCM electrode and their applications in various fields and has positive significance to promote the development of QCM sensor technology.