Modeling, simulation, and fabrication of a PZT valveless micropump
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A micropump is one of the most important elements in a micro-total analysis system used for rapid chemical and biological analysis. To date, different kinds of micropumps have been designed, fabricated, tested, and implemented. Among them, a PZT valveless micropump is receiving increasing attentions due to its unique advantages over a conventional check-type micropump. A valveless micropump is short of fatigue and wear of movable part. Without movable parts in the device may avoid high-pressure drop across the valves. It is expected that a valveless micropump has higher reliability and a longer lifetime. In particular, a valveless micropump is unique for delivering solutions with particles. Diffuser and nozzle elements direction dependent flow characteristics are quantitatively studied and summarized. From diffuser and nozzle flow characteristics, the working principle of the valveless micropump is presented. Based on fluidic mechanics and solid mechanics, a dynamic model for the PZT actuated valveless micropump is developed. The flow rate and backpressure are the most important performances for the valveless micropump. Considering nonlinear pressure loss in the nozzle, a numerical simulation method is chosen to study the valveless micropump performance. The simulation is studied in low frequency domain. The effects of several key parameters on the micropump performances are discussed. These key parameters include passive plate dimensions, PZT dimensions, and nozzle dimensions. An optimized micropump design is presented following the numerical simulation. The optimized dimensions for the micropump include 500 microns for the membrane thickness, 25 mm for the membrane radius, 80 microns for the nozzle neck and 400 microns for the nozzle length. The fabrication process for the valveless micropump is also implemented. Two major problems associated with the fabrication process were experimentally investigated. The fabrication process is revised accordingly.