Design And Fabrication Of The Micropump And The Microvalve Based On MEMS Technology

Micro-electro-mechanical Systems (MEMS) has broad prospect in many fields and becomesone of the most important development direction of the microelectronics. The micropump andmicrovalve as key control devices in microflow system are becoming one of hot point in MEMSresearch because of a broad application foreground in medication transportation, DNA composing,micro-fluidic supply and precision control, CMOS chip cooling system, micro-dialyse, micro-pushand micro-secondary planet.The development of MEMS, especially of micromachining techniques, micropumps andmicrovalves, are introduced in detail in this dissertation. The main objectives of this dissertationare the design, optimization and fabrication of mciropumps and microvalves as well as theresearch on related processes, test methods and theories, which are based on the recent worldwidedevelopments in this field and the domestic technique condition and demand.To lower threshold pressure, control the flow direction efficiently and enlarge the packagetolerance. The properties of two kinds of microvalves are analyzed thoroughly. Based on thetheoretical analyses, microvalves with cantilever flap or four spring beam, valve seat and valvehole are designed, optimized and fabricated, which are made of SU-8. The process parameters ofSU-8 are determined through experiments. The through-flow characteristics of microvalves aretested. The maximum forward flow rate of the cantilever flap microvalve and four spring beammicrovalve are more than 5.78ml/min and 7 ml/min respectively. The minimum backward flowrate of cantilever flap microvalve and four spring beam microvalve are below21μL/min and 10μL/min respectively.The four kinds of micropumps based on MEMS technology were fabricated and theirperformances were tested using air and liquid as medium, the tested results show that the height ofmicorpump chamber, the dimension and thickness of micorvalve, the dimension and place ofmicrovalve seat and the thickness of membrane affect the performances of micopump and theoptimal working frequency. There is an optimal height of micorpump chamber when micropurnphave good features. The influence of air bubble was investigated from theory and experiment andability of tolerance air bubble rest with dead volume of chamber, volume of out and in pipes,displacement of membrane and working medium.The micropump is driven by a PZT bimorph that is mounted on the designed installer. Theinlet and outlet are on the same side and the driving structure is on the other side. The roundpump-membrane and round chamber can effectively avoid centralizing stress and producing airbubble and result in rinsing chamber easy. The maximum flow of DF-ZX07-03D micropump is6.7ml/min and the back pressure is 16.9KPa. The precision of flow control is 1μL/min.