Culbertson CT, Ramsey RS, Ramsey JM
Oak Ridge National Laboratory, Tennessee 37831-2008, USA.
Anal Chem. 2000 May 15;72(10):2285-91. doi: 10.1021/ac9912202.
The theory behind and operation of an electroosmotically induced hydraulic pump for microfluidic devices is reported. This microchip functional element consists of a tee intersection with one inlet channel and two outlet channels. The inlet channel is maintained at high voltage while one outlet channel is kept at ground and the other channel has no electric potential applied. A pressure-induced flow of buffer is created in both outlet channels of the tee by reducing electroosmosis in the ground channel relative to that of the inlet channel. Spatially selective reduction of electroosmosis is accomplished by coating the walls of the ground channel with a viscous polymer. The pump is shown to differentially transport ions down the two outlet channels. This ion discrimination ability of the pump is examined as a function of an analyte's electrophoretic velocity. In addition, we demonstrate that an anion can be rejected from the ground channel and made to flow only into the field-free channel if the electrophoretic velocity of the anion is greater than the pressure-generated flow in the ground channel. The velocity threshold at which anion rejection occurs can be selectively tuned by changing the flow resistance in the field-free channel relative to the ground channel.
报道了用于微流控装置的电渗诱导液压泵的原理及操作。这种微芯片功能元件由一个带有一个入口通道和两个出口通道的三通交叉点组成。入口通道保持高电压，一个出口通道接地，另一个通道不施加电势。通过相对于入口通道降低接地通道中的电渗，在三通的两个出口通道中产生压力诱导的缓冲液流动。通过用粘性聚合物涂覆接地通道的壁来实现电渗的空间选择性降低。该泵被证明能使离子沿两个出口通道进行差异传输。研究了该泵的这种离子区分能力与分析物电泳速度的关系。此外，我们证明，如果阴离子的电泳速度大于接地通道中压力产生的流速，阴离子可以从接地通道被排斥，仅流入无电场通道。通过改变无电场通道相对于接地通道的流动阻力，可以选择性地调节阴离子排斥发生时的速度阈值。
