Maximization of the capillary pump efficiency in microfluidics

摘要

This paper studies the efficiency of capillary pump analytically in circular, square and rectangular channels with resultsverified by experiment. The effect of liquid momentum is analyzed with respect to channel size and equations aredeveloped to enable most efficient fluid pumping. It is found that the momentum term is negligible at channel cross-cutarea < 0.1 mm~2 while it has a significant contribution at > 0.3 mm~2 region. The optimized equations show that the mostefficient pumping and thereby the quickest liquid filling is accomplished in square shaped channel when compared withrectangular and circular channels. Generally, the longer the filling distance, or the longer the filling time, the larger thechannel size is required after optimization, and vice versa. For the rectangular channel with channel height fixed, thechannel width requirement to maximize the ability of capillary pump is obtained and discussed. Experimental verificationsare conducted based on the measurement of filling distance versus time, and the simulation results are well correlatedwith the testing results. The equations developed in the paper provide a reference for the microfluidic channeldesign, such that the channel filling speed can be maximized.