| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 87 === Microfluidic devices technology has been studied for about 20 years. With the improving capability in Micro-Electro-Mechanical-System (MEMS) technology for microfabrication, the usage of microfluidic devices is getting much broader and can be found in many different areas and applications. Also the device system is getting more sophisticated in term of their structure and performance. Because of the increasing demand on the better performance of the microfluidic devices, many theoretical works as well as experimental ones have been carried out based on fundamental physical and chemical phenomena and their analysis and simulation.
The main purpose of this study is to establish a flow rate theory which can simulate a piezoelectric valve-less micropump, so that the important characteristics of the micropump can be understood and predicted. Instead of passive check valves, a piezoelectric valve-less micropump adopts both nozzle and diffuser elements for flow controlling. Based on the equation of continuity, this research considers the effects of pressure loss coefficients of nozzle and diffuser and the inlet and outlet pressures on the overall flow rate of a valve-less micropump. In combining both numerical techniques and a finite element analysis package (ANSYS), a model has been established to estimate and predict the flow rate of a valve-less micropump.
As one of the results of this study is that there exists a delay phenomenon between the pressure within the chamber and the driving voltage on the piezoelectric material. Also, by comparing the simulated results based on our model with the experimental data found in the literature, we find that our simulated results can match closer to the experimental data than earlier works, especially in the low-frequency range. With this analysis model, micropump designer can find important and useful information and knowledge on the characteristics and performance of the pump, prior to the actual fabrication of the micropump.
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