Study Of Valveless Piezoelectric Micropump Based On Parallel Double Chambers

Microfluidic systems have become the research foucs in MEMS field because extensive applications in many fields such as shipping industry, microbiological chips etc. Driving the liquid flows, micropump is one of the most important components of microfluidic system. Improvement about micropumps, such as miniaturization, integration, increasing the flow rate and optimizing the pumping performance, have pratical significance to the whole development of microfluidic systems. Valveless micropump, in which nozzle/diffuser pipes take the role of directional valves, can pump liquid single directionally for the characteristic of the flow channel asymmetry. Valveless micropumps have become the hot spot of micropump study for lots advantages as small volume, simple structure, easy to be fabricated ,can to transport most kinds of liquid.In the paper, the principle of PZT buzzer and characteristics of microfluid are presented, a kind of valveless piezoelectric micropump based on parallel double chambers is introduced and tested. The driving performance of the PZT buzzer is simulated by Finite Element Analysis (FEA) software ANSYS, and curves between structure parameters and center displacement / frequency of PZT buzzer are obtained. The nozzle/diffuser pipes' structure parameters are optimized by numerical simulation by using ANSYS FLOTRAN and CFX software, and flow characteristic parameters such as Reynolds number, flow rate and pressure distribution in the pipe are researched. The chamber is produced on glass, and nozzle/diffuser pipes are fabricated on <100> silicon by selective-wet etch using MEMS technology. These two components are glued with PZT buzzer together to form micropumps with single chamber and micropumps with parallel double chambers. The max center diaplacement and primary frequency of the PZT buzzer is measured by current displacement sensor, and the flow rates of micropumps in different conditions are tested by test system. The results of micropump with double chambers are compared with the micropump with single chamber. The results shows that the optimization widest diameter of nozzle/diffuer pipe of 400μm in length is 800μm, the best working frequency of the micropump with single chamber is 2600Hz , the max work voltage of the PZT buzzer is110V, and the flow rate is about 115μl/min. The best working frequency of the micropump with double chambers is 2700Hz , and the flow rate is about 151.7μl/min which is 1.3 times of the flow rate of single micropump.