旅波式介電幫浦之實驗研究

Abstract

本論文以實驗方式探討旅波介電泳幫浦。該幫浦為一可適用於微流道中輸送兩相懸浮 流之幫浦，比如說用於輸送我們的血。本幫浦為一直型微流道，其截面為矩形，同時在壁面 鍍有電極。當將一交流且同時擁有相位差之訊號施以電極上，傳統介電泳及旅波式介電泳將 會驅使懸浮粒子或是細胞運動。當旅波介電力主導懸浮粒子運動時，粒子單方向移動並拖曳 介質前行，因此兩相懸浮流體即被傳送。我們使用微機電製程技術製造出該幫浦，並驗證該 幫浦的確適用於輸送人血上。同時，我們探討該幫浦在不同參數下之性能，其中包含了電 壓，頻率，鄰近電極之相位差，所使用之電極數，懸浮粒子之濃度，不同之懸浮粒子，輔助 電極之使用，以及不同之訊號源（訊號產生器及IC）。我們使用以上參數可得到以下結論： 以四相位（相位差90度），多組電極，較大的粒子，同時使用輔助電極，將會使得粒子以較 快的速度移動。以我們的實驗為例，人血之紅血球細胞在6伏特，10MHz，90度相位差以及 擁有輔助電極及24根驅動電極作用之下，以每秒28.4μm之速度移動。該幫浦同時亦可以以IC 驅動，這證明了將該幫浦微小化之可能性。我們可將此幫浦應用於生醫領域。

This thesis studies experimentally the traveling wave dielectrophoretic pump, which is a micropump suitable for delivering two-phase suspension medium, such as our blood. The pump is essentially a straight microchannel with square cross section with array of electrodes built on one of its walls. Ac voltage is applied to the electrodes with a certain phase shift on neighboring electrodes. Both conventional and traveling wave dielectrophorsis are generated and drive the suspended particles (or cells) in motion. When the traveling wave dielectrophoretic force dominates the particle motion, the particles move along the direction of increasing phase if the imaginary part of the Clausius factor is positive (or vice versa), drag their surrounding fluid, and thus the whole medium is transported. We first manufactured the pump via MEMS techniques and demonstrate the feasibility of the above idea for pumping using human blood. Then we studied the performance of the pump for different parameters, including applied electric voltage, electric frequency, phase shift for neighboring electrodes, number of electrodes, concentration of suspended particles (by varying blood/saline ratio), different particles (blood cells of wister and human), without and with assistant electrodes before the normal electrode array, and different driving sources (functional generator or small IC chip). It is found that we have larger cell velocity for larger voltage, more electrodes, 90o phase shift (in comparing with 120o), larger cells, and with assistant electrodes. Typical cell velocity of human blood reaches 28.4 μm/s for 6 volts, 10 MHz, 90 phase shift and 24 electrodes with assistant electrodes. The pump also works when it is integrated with a IC chip, which shows the possibilities of building a small portable device. The result may find application in biomedical area.