Chen Yen-Fu, Chen Hsuan-Yi, Sheng Yu-Jane, Tsao Heng-Kwong
Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China.
Department of Physics, National Central University, Jhongli, Taiwan 320, Republic of China.
J Chem Phys. 2017 Jan 7;146(1):014902. doi: 10.1063/1.4973228.
The steady ratchet transport of run-and-tumble nanoswimmers in a 3D microfluidic channel constructed by periodic chambers separated by half-cylinder funnels is explored by dissipative particle dynamics. Two regions in a chamber are identified: rectification and active diffusion. While the concentration gradient is driven by the concentration jump in the rectification region, the ratchet current is dominated by the diffusion rate in the active diffusion region, which is classified into normal and Knudsen types. The former obeys Fick's law and is proportional to vτ, where v is the self-propulsion velocity and τ the run time. In addition, autonomous pumping of fluids is induced by aligned force dipoles associated with nanoswimmers accumulated near funnels, similar to the mechanism of bacteria carpet. The direction of fluid flow is the same as that of the ratchet current but the former is one order of magnitude smaller than the latter. Thus, the fluid velocity depends on the characteristics of nanoswimmers.
通过耗散粒子动力学研究了在由半圆柱形漏斗分隔的周期性腔室构成的三维微流体通道中，“奔跑-翻滚”纳米游动者的稳定棘轮输运。在一个腔室内确定了两个区域：整流区和主动扩散区。虽然浓度梯度由整流区的浓度跃升驱动，但棘轮电流由主动扩散区的扩散速率主导，主动扩散区分为正常型和克努森型。前者服从菲克定律，且与vτ成正比，其中v是自推进速度，τ是奔跑时间。此外，类似于细菌毯的机制，与聚集在漏斗附近的纳米游动者相关的排列力偶极会引起流体的自主泵送。流体流动方向与棘轮电流方向相同，但前者比后者小一个数量级。因此，流体速度取决于纳米游动者的特性。
