| In recent years, with the development of society and economy, in medical diagnostics, environmental health, food safety and other areas, more and more security problems occurred frequently. These problems, or even disaster, mostly caused by such dangerous substances or biological, ebola virus, SARS virus, avian influenza virus, melamine, or red tide. And one of the most important reason why these disasters has great destructive power, is the lack of an effective, real-time POCT (Point-of-Care Testing) detection technology. Researchers need a few days or weeks even, months to get the measurement results by the traditional biochemical testing methods, and vaccine research will take a long time. Therefore the research of a real-time detection platform, with an efficient and rapid drug screening function, has become a serious problem at home and abroad. With the development of microelectronics, micro-electromechanical systems (MEMS), biosensors has became more automated, miniaturized and intelligent. These techniques can be used to establish the real-time detection platform. At the same time, piezoelectric biosensor has became more useful in POCT field for its high sensitivity, such as quartz crystal microbalance (QCM) (ng level), Surface Acoustic Wave (SAW) (pg level). The research of piezoelectric biosensor can provide an effective, real-time POCT detection technology for the use in the areas of health healthcare, clinical research, drug screening, food inspection, marine environmental protection, etc. With the development of industrial, this POCT detection technology will constantly create more value for our society.This study focus on the piezoelectric biosensor, such as QCM and Love wave sensor. By studying the mechanism of the piezoelectric effect, two rapid, real-time and effective POCT detection systems will be developed combined with the bond rupture technique. The main content of the dissertation are summarized below.1. The research of mechanical wave propagation mechanism of piezoelectric crystals in QCM and Love wave device.The coupling effects between mechanical energy and electrical energy exist in piezoelectric crystals. The research of mechanical wave propagation mechanism is carried by the piezoelectric equations in anisotropic quartz crystal:there are thickness shear vibration in QCM, and the theoretic sensitivity of QCM is derived; In Love wave device, the wave equation of Love wave is derived in the Love wave propagation half-space model, meanwhile the theoretic sensitivity and dispersion equation are also derived.2. The development of QCM bond rupture system.Based on bond ruture technique, a QCM bond rupture system is developed with the DDS (Direct Digital Synthesizer), VGA (Variable Gain Amplifier) and high-speed signal acquisition system, which has excellent design parameters. An efficient algorithm of resonant frequency tracking and bond rupture is also designed. Besides, an economical and disposable detecting cell of QCM is developed for the detection of viruses, bacteria and other substances disasters.3. Love wave device simulation.With the development of MEMS and biosensors, Simulation has become one of the most effective method to reduce costs and enhance the nondefective rate unceasingly. Firstly, the mechanism of finite element method is studied, secondly, the different kinds of the piezoelectric substrate and the waveguide layer materials are srudied. And then, a 3D FEM model has been created and defined to simulate the displacement response of the acoustic wave system, and a 2D model has been established to simulate the mass sensitivity with different composite structures of 128° YX LiNbO3,36° YX LiTaO3, ST-quartz-PMMA and 128° YX LiNbO3,36° YX LiTaO3 and ST-quartz-SiO2, in order to find the best material for Love wave sensor.4. Develop the Love wave sensor, and establish the detecting sysrem.Based on the optimized Love wave structure, the research of lithography techniques and manufacturing processes for Love wave is carried. Then a Love wave device has been developed, whick works at 124.59MHz. The sensitivity of the Love wave device is 49.518Hz/(ng·cm-2). Furthermore, a detecting cell is developed for the measuring.In conclusion, a QCM bond rupture system is developed for POCT detecting. And on this basis, a Love wave sensor is developed for its higher sensitivity. These two platforms can effectively improve the speed of drug screening and seedling. It is more significance for the rapid detection of biological substances disasters, environmental protection and so on. And more useful to solve the security problems in medical diagnostics, environmental health, food safety and other areas. It can provide a rapid, real-time, high accuracy and in situ POCT detecting system for our society. |
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