Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921, United States.
Anal Chem. 2015 Jun 16;87(12):6389-96. doi: 10.1021/acs.analchem.5b01432. Epub 2015 Jun 2.
Many of the fluids encountered in chemical and biomedical applications exhibit non-Newtonian behavior. However, the majority of current particle separation methods have been demonstrated in Newtonian fluids only. This work presents an experimental study of continuous particle separation in viscoelastic solutions via a combined action of elastic and inertial lift forces, which we term elasto-inertial pinched flow fractionation (eiPFF). The parametric effects on eiPFF are systematically investigated in terms of dimensionless numbers. It is found that eiPFF offers much higher particle throughput and separation resolution than the traditional steric effects-based PFF. Moreover, eiPFF works most efficiently when the Reynolds number, Re, is of order 1 and hence fills perfectly into the gap of our recently proposed inertia-enhanced PFF (iPFF) technique (Anal. Chem. 2015, 87, 4560-4565) that favors Re of the order 10 or more. However, the particle separation via eiPFF does not increase monotonically with the elasticity number at higher polymer concentrations and is strongly affected by the aspect ratio of channel width to height, both of which have not been previously reported. More surprisingly, the elasto-inertial deflection of small particles can be even greater than that of large particles in a high-aspect-ratio channel for Re less than 1.
许多在化学和生物医学应用中遇到的流体表现出非牛顿行为。然而，目前大多数的粒子分离方法仅在牛顿流体中得到了验证。本工作通过弹性和惯性升力的联合作用，对粘弹性溶液中的连续粒子分离进行了实验研究，我们称之为弹惯性夹流分级分离（eiPFF）。通过无量纲数系统地研究了 eiPFF 的参数效应。结果表明，eiPFF 比传统基于位阻效应的 PFF 具有更高的粒子通量和分离分辨率。此外，当雷诺数 Re 为 1 左右时，eiPFF 效率最高，因此完全填补了我们最近提出的惯性增强 PFF（iPFF）技术的空白（Anal. Chem. 2015, 87, 4560-4565），该技术有利于 Re 为 10 或更高。然而，在较高聚合物浓度下，通过 eiPFF 进行的粒子分离并不随弹性数单调增加，并且强烈受到通道宽度与高度之比的影响，这两者以前都没有报道过。更令人惊讶的是，对于 Re 小于 1 的高纵横比通道，小颗粒的弹惯性偏转角甚至可以大于大颗粒。
