Lichtenberg J, Verpoorte E, de Rooij N F
SAMLAB, Institute of Microtechnology, University of Neuchâtel, Switzerland.
Electrophoresis. 2001 Jan;22(2):258-71. doi: 10.1002/1522-2683(200101)22:2<258::AID-ELPS258>3.0.CO;2-4.
A microchip structure for field amplification stacking (FAS) was developed, which allowed the formation of comparatively long, volumetrically defined sample plugs with a minimal electrophoretic bias. Up to 20-fold signal gains were achieved by injection and separation of 400 microm long plugs in a 7.5 cm long channel. We studied fluidic effects arising when solutions with mismatched ionic strengths are electrokinetically handled on microchips. In particular, the generation of pressure-driven Poiseuille flow effects in the capillary system due to different electroosmotic flow velocities in adjacent solution zones could clearly be observed by video imaging. The formation of a sample plug, stacking of the analyte and subsequent release into the separation column showed that careful control of electric fields in the side channels of the injection element is essential. To further improve the signal gain, a new chip layout was developed for full-column stacking with subsequent sample matrix removal by polarity switching. The design features a coupled-column structure with separate stacking and capillary electrophoresis (CE) channels, showing signal enhancements of up to 65-fold for a 69 mm long stacking channel.
开发了一种用于场放大堆积（FAS）的微芯片结构，该结构能够以最小的电泳偏差形成相对较长的、体积确定的样品塞。通过在7.5厘米长的通道中进样和分离400微米长的样品塞，实现了高达20倍的信号增益。我们研究了在微芯片上电动处理离子强度不匹配的溶液时产生的流体效应。特别是，通过视频成像可以清楚地观察到，由于相邻溶液区域中不同的电渗流速度，在毛细管系统中产生了压力驱动的泊肃叶流效应。样品塞的形成、分析物的堆积以及随后释放到分离柱中表明，仔细控制进样元件侧通道中的电场至关重要。为了进一步提高信号增益，开发了一种新的芯片布局，用于全柱堆积，随后通过极性切换去除样品基质。该设计具有耦合柱结构，带有单独的堆积通道和毛细管电泳（CE）通道，对于69毫米长的堆积通道，信号增强高达65倍。
