Design And Construct Differential Quartz Crystal Microbalance

Quartz Crystal Microbalance (QCM) is a new type of micro-mass sensor which allows accurate measurements of mass,viscosity and shear modulus on nano-scale. It has been widely in many fields,such as electrochemistry,biomedicine,organic chemistry,analytical chemistry,physics,etc,because of its high precision, good stability, small size and simple structure. This thesis is mainly about several aspects as follows:1. Introduce the technical background,basic structure of QCM. We discuss Domestic and foreign research present situation of QCM.We discuss the factors that affect the QCM measurement results.2. Develop a novel quartz crystal oscillator. The oscillator works on the 3 overtone of the crystal, can drive the crystal under liquid phase, and can measure the series resonant frequency the resistance and dissipation of the crystal . We use a band pass filter in the oscillator, so it can work on the 3 over tone of the crystal ,and with same method it can also works on 5 overtone.3. We designed a high speed data-acquisition circuit of QCM with USB2.0 interface. It adopts the technique of high speed and high precision A/D converter and frequency measurement with equal-precision.It has two analog channels and can compare the differential data from the two channels.4. We construct difference QCM by using the QCM driving circuit and data acquisition electric circuit,We program to analy data.It is easy to operate.Our system has the high scientific research value and the commercial value.