Continuous SPLITT Fractionation

这项建议研究了一种基于流动的分离技术，用于分离颗粒。分离在通常厚度小于5 mm、宽约2 cm、长约20 cm的矩形流室中进行。在通道的入口处，沿管子纵向延伸几毫米的分离板将通道的入口区分割成两半。载液被泵入分离器一侧的腔室中，而含有颗粒的流体在另一侧被引入。当流体通过分离器边缘时，会产生两相相邻的泊松埃流，壁面边界附近的流体移动速度比通道中心的流体慢。当颗粒沿通道的长度被携带时，在垂直于流轴的方向上施加的场迫使颗粒向载体流迁移。引力和电场力是可以使用的场的两个例子。场对粒子施加的力的大小取决于特定的粒子特性，如果粒子之间的特性不同，则力的大小也不同，这一事实影响了分离。这种特性的例子是大小，它会导致不同的引力和电荷。受外力作用较强的颗粒进一步迁移到载体流中，在那里它们被较慢移动的流体卷吸而减速。在粒子向下游平移了一定距离后，受作用力不那么强的粒子位于更中心的位置，并且比作用更强的粒子向下游移动得更远，这些粒子更接近边界，没有向下游推进。在过去的25年里，PI发展了利用沿流动方向颗粒之间不断发展的分离距离来收集颗粒的技术。当流体离开通道时，那些在中心附近流动的流体首先洗脱并可以收集，而那些在边界附近流动的流体稍后洗脱并可以单独收集。PI将这种技术命名为FFF，用于场流分馏。在FFF的开发过程中，放大被证明是困难的，该技术只能用于分析测量，因为收获的数量非常少。与FFF不同，获取分离的另一种技术是在下游使用分离器，将流分割为两个退出的流。一个流将包含靠近中心移动的粒子，而另一个流将包含靠近通道单元边界移动的粒子。PI将这种分离称为连续分裂分离的CSF，并自1985年以来一直致力于CSF。提案的第11-19条)。这项建议中建议的研究涉及细胞的放大，改善其性能，并检查不同的分离机制。

This proposal studies a flow based separation technique for fractionating particles. The separation is carried out in a rectangular flow chamber which is generally under 5 mm in thickness, and approximately 2 cm in width and 20 cm in length. At the entrance of the channel, a splitter plate which extends lengthwise a few millimeters down the tube, partitions the inlet region of the channel into two halves. A carrier fluid is pumped into the chamber on one side of the splitter, and the fluid containing the particles is introduced on the other side. As the fluids pass the splitter edge, a two phase adjacent Poiseuille flow is created with fluid near the wall boundaries moving slower than fluid in the center of the channel. As the particles are carried along the length of the channel, a field applied in a direction perpendicular to the flow axis forces the particles to migrate towards the carrier stream. Gravitational and electric forces are two examples of fields which can be used. The separation is effected by the fact that the magnitude of the force exerted by the field on the particles depends on a particular particle characteristic, and if that characteristic differs between particles then so does the magnitude of the force. Examples of such characteristics are size which would result in a different gravitational force and electric charge. Particles more strongly acted upon by the applied force migrate further into the carrier stream where they decelerate as they are entrained by slower moving fluid. After the particles have translated a certain distance downstream, particles which are not acted upon as strongly by the force are more centrally located and have moved further downstream than particles more strongly acted upon which are nearer the boundary and have not progressed as far downstream. During the last two and one-half decades, the PI developed the technique of collecting the particles by taking advantages of the developing separation distance between the particles along the flow direction. As the fluid leaves the channel, those travelling near the center elute first and can be collected, while those travelling near the boundary elute later and can be collected separately. The PI has termed this techniques FFF for field flow fractionation. In the development of FFF, scale-up proved difficult and the technique could only be used for analytical measurement since the quantities harvested were very small. In contrast to FFF, a different technique for harvesting the separation is to use a splitter at the downstream end to divide the stream into two exiting streams. One stream would contain the particles moving near the center, while the other would contain the particles moving closer to the channel cell boundary. The PI has termed this separation CSF for continuous SPLITT fractionation and has been working on CSF since 1985 (refs. 11-19 of the proposal). The research suggested in this proposal is concerned with scaleup of the cell, improving its performance, and examining different separation mechanisms.