Investigation Of Piezoelectric Valveless Micropump For Microfluidic Chips

Microfluid chips are an important part of micro total analysis system. It's based on MEMS technology, with the advantages of liquid flow controllable, consuming fewer samples and analyzing quickly. It has a very broad application prospect in the field of biomedical detection, drug synthesis, and chemical analysis. As the power source of microfluid chips, micropump is a main determinant of the whole analysis system, which is the hotspot in this field. In this thesis, a valveless piezoelectric micropump used for microfluidic chips is presented. During this research, the structure of this micropump is optimized, and the fabrication of the micropump is accomplished later. In order to realize the application in microfluidic chips, the micropump is integrated to a microfluidic chip. The works carried out can be mainly summarized as follows:1) The working principle of the valueless micropump is simply introduced. And from the hydrodynamics theory, the output flow rate equation of valueless micropumps is derived. Furthermore, both the structure and usage of the piezoelectric actuator, and the optimization of diffuser/nozzle elements are analyzed. At last, a design proposal for the valveless pump is given.2) Via the study of the characteristics of glass, the fabrication on the glass wafer is researched, including the processes of photographic and wet etching. Accordingly, the fabrication processes for depth channels on the glass are obtained, which provides high surface quality, as well as efficient glass-glass and glass-PDMS bonding processes.3) Using commercial materials, a low-cost valveless piezoelectric micropump is produced. More, a power supply for piezoelectric actuators with multi-wave, adjustable frequency and voltage is developed, which can provide reliable driving equipment for micropumps. Finally, the performances of this micropump, such as flow rate and backpressure, are characterized, and the optimal driving conditions are also obtained.4) As the power source, the micropump is integrated to a microfluidic chip, which can improve the automation of microfluidic chips. In addition, the integration of micropump in microcooling systems is discussed, which prepares for the further research.