Lacharme Frédéric, Gijs Martin A M
Institute of Microelectronics and Microsystems, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Electrophoresis. 2006 Jul;27(14):2924-32. doi: 10.1002/elps.200500723.
We propose two variants of a new injection technique for use in electrophoresis microchips, called "front gate pressure injection" and "back gate pressure injection", that both enable a controlled and reproducible sample introduction with reduced bias compared to electrokinetic gated injection. A continuous flow of a test solution of fluorescein/rhodamine B in 20 mM Tris/boric acid buffer (pH 8.6) sample test solution is electrokinetically driven near to the entrance of the separation channel, using a single voltage (3 kV) that is constant in time. A sample plug is injected in the separation channel by a pressure pulse of the order of 0.1 s. The latter is generated using the mechanical deflection of a PDMS membrane that is loosely placed on a dedicated chip reservoir. The analysis of the peak area ratio of the separated compounds demonstrates a nearly constant sample composition when using pressure-based injection. A small remaining injection bias for the shortest membrane deflection times can be attributed to a dilution effect of the charged compound due to the presence of an electrical field transverse to the sample flow boundary in the channel junction.
我们提出了一种用于电泳微芯片的新型进样技术的两种变体，分别称为“前栅极压力进样”和“后栅极压力进样”。与电动门控进样相比，这两种变体都能实现可控且可重复的样品引入，偏差更小。在20 mM Tris/硼酸缓冲液（pH 8.6）样品测试溶液中，使用单一恒定电压（3 kV），通过电动驱动使含有荧光素/罗丹明B的测试溶液连续流动至分离通道入口附近。通过约0.1 s的压力脉冲在分离通道中注入样品塞。该压力脉冲是利用松散放置在专用芯片储液器上的PDMS膜的机械偏转产生的。对分离化合物的峰面积比分析表明，使用基于压力的进样时，样品组成几乎恒定。对于最短的膜偏转时间，仍存在较小的进样偏差，这可归因于通道连接处与样品流边界垂直的电场导致带电化合物的稀释效应。
