Cytometry and Velocimetry on a Microfluidic Chip Using Polyelectrolytic Salt Bridges

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• 作者：Honggu Chun ; Taek Dong Chung ; and Hee Chan Kim
• 刊名：Analytical Chemistry
• 出版年：2005
• 出版时间：April 15, 2005
• 年：2005
• 卷：77
• 期：8
• 页码：2490 - 2495
• 全文大小：224K
• 年卷期：v.77,no.8(April 15, 2005)
• ISSN：1520-6882

文摘

This paper reports a polyelectrolytic salt bridge-basedelectrode (PSBE), which is a key embedded unit in amicrochip device that can size-selectively count microparticles and measure their velocities. The constructionof salt bridges at specific locations within a microfluidicchip enables dc-driven electrical detection to be performed successfully. This is expected to be a competitivealternative to the optical methods currently used inconventional cell sorters. The PSBEs were fabricated byirradiating ultraviolet light over a patterned mask on theparts of interest, which were filled with an aqueousmonomer solution containing diallyldimethylammoniumchloride. A pair of such PSBEs was easily formed at thetwo lateral branches perpendicular to the main microchannel and was found to be very useful for dc impedometry. The human blood cells as well as the fluorescentmicrobeads passing between the two PSBEs producedimpedance signals in proportional to their size. Theinformation about the velocity of a microparticle wasextracted from a doublet of the dc impedance signals,which were generated when cells or microbeads sequentially passed through two PSBE pairs separated from eachother by a fixed distance. The plot of peak amplitudeversus velocity of the moving microbeads and cellsindicated only a slight correlation between the size andthe velocity, which means that the peak amplitude of thedc impedance signals alone can provide information aboutthe size of the cells in a mixture. The experimental resultsshowed a screening rate of over 1000 cells s^-1 and avelocity of the cells of over 100 mm s^-1. Compared withthe previously suggested electrical detection system basedon metal electrodes, the sensitivity and selectivity in celldetection were remarkably improved. In addition, thedetection unit including the operating circuit becameinnovatively simple and the whole device could be miniaturized.