Based On The Analysis Of Heavy Metal Ions In The Qcm Design Fruit

With the heavy metal pollution is increasingly serious， we need a newmethod,which is inexpensive,easy to use and accurate,to detect it,so that we cancontrol it effictively.Quartz Crystal Microbalance（QCM）, as a new type of sensormeasurement technology, is built up in the1960s.It is widely used because of its manyadvantages, such as the response of a broad spectrum,high sensitivity,simplestructure,low cost and so on.In this thesis,we design a QCM probe,and according to Sauerbrey theory,we usethe probe to detedct heavy metal Cu²⁺in the fruits,indicating the feasibility of theQCM in quality testing. The main content of this paper are as follows:1.The hazards and decection methods have been described.The history of thedevelopment，the application and the status quo both at home and abroad of QCM havebeen studied. The significance of heavy metals detection has been given out.2.The theoretical basis of QCM measurement are described. The piezoelectriceffect of quartz crystals is explained,and the theoretical formulas for QCM detectingboth in gas and liquid are derived.3.QCM probe is designed,and on the basis of trap theory, QCM electrodestructures are analyzed. A resonator based on the elliptical ring electrodes of the ladderconvex structure is present. Matlab is used to its simulation.4.On the basis of the analysis of frequency measurement principle and QCMequivalent circuit model, the double II matching network used in the QCMmeasurement is designed.5.By measuring the Cu²⁺in the kiwifruit, the specific process of heavy metalmeasure by QCM is been stated. The Cu²⁺in apple,pear,orange,lemon are also mesured.When comared with the standard, the results are satisfactory. The source of deviationsin the measurement results are also summarized.