Design, testing and optimization of a micropump for cryogenic spot cooling applications

The performance of two micropumps with different electrode designs in liquid N/sub 2/ was investigated in this study. One of the experimental challenges was developing a method for measuring the flow rate of the liquid N/sub 2/. By combining a numerical model of the non-isothermal flow of the liquid N/sub 2/ around the loop and the experimental measurements of the temperatures around the flow loop, the liquid N/sub 2/ flow rates could be determined accurately enough to compare the pumping performance of these micropumps. The first tested micropump had an electrode spacing of 20 /spl mu/m and an electrode pair spacing of 80 /spl mu/m, while the second pump had an electrode spacing of 50 /spl mu/m and electrode-pair spacing of 200 /spl mu/m. The results showed that both micropumps pumped sufficient liquid N/sub 2/ to cool a typical superconductive sensor or other low power device. For both pumps, the pumping capacities increased with increasing EHD voltage. The pump with the smaller electrode spacing generated a higher flow rate at a lower applied voltage. This pump generated flow rates as high as 10 mL/min at an applied voltage of 500 V.