Department of Mechanical Engineering and Science , Kyoto University , Kyotodaigakukatsura, Kyoto , Kyoto 615-8540 , Japan.
Anal Chem. 2019 May 21;91(10):6462-6470. doi: 10.1021/acs.analchem.8b04821. Epub 2019 May 3.
In this study, a technique for particle streamwise timing, spacing and velocity control (alignment) in microchannel flow by controlling the forces exerted on the particle in space and time, was developed. In the present technique, the timing of particles crossing a certain position in microchannel flow with a specific interval and the particle velocity are controlled by applying acceleration and deceleration forces periodically in the streamwise direction and activating them periodically. The force is produced by a dielectrophoretic force using ladder-type electrodes embedded in the microfluidic device and is turned on and off in a cycle. The timing of particles crossing a certain position can be changed by adjusting the phase of the on-off cycle, i.e., the phase of the voltage signal. In the experiment, timing and velocity were measured at the inlet and outlet of ladder-type regions for Jurkat cells and particles of some variation in size, and probability density functions for the deviation of these values from the equilibrium (aligned) state were evaluated. Further, we will discuss the motion characteristics of the particles numerically and experimentally to understand the mechanism and evaluate the performance of the particle timing control and alignment using the present technique. The results confirm that the particles randomly distributed at the inlet of ladder-type electrode regions are controlled to flow with even spacing at a specific velocity. Moreover, the timing of the particles passing a specific location in the ladder-type electrode region was synchronized with the activated/nonactivated cycle of the applied force and could be specified.
在这项研究中，开发了一种通过控制粒子在空间和时间上的受力来实现微通道流中粒子流的定时、间距和速度控制（对准）的技术。在本技术中，通过在流向上周期性地施加加速和减速力并周期性地激活它们来控制粒子以特定间隔穿过微通道流中特定位置的定时和粒子速度。力是通过嵌入微流控装置中的梯形电极的介电泳力产生的，并在一个周期内打开和关闭。通过调整开-关周期的相位（即电压信号的相位），可以改变粒子穿过某个位置的定时。在实验中，在梯型区域的入口和出口处测量 Jurkat 细胞和尺寸略有变化的粒子的定时和速度，并评估这些值偏离平衡（对准）状态的偏差的概率密度函数。此外，我们将通过数值和实验讨论粒子的运动特性，以了解使用本技术进行粒子定时控制和对准的机制和性能。结果证实，随机分布在梯型电极区域入口处的粒子被控制以特定速度均匀间隔流动。此外，粒子通过梯型电极区域中特定位置的定时与施加力的激活/非激活周期同步，并可以指定。
