Lateral migration of dual droplet trains in a double spiral microchannel

Microfluidic droplets have emerged as novel platforms for chemical and biological applications. Manipulation of droplets has thus attracted increasing attention. Different from solid particles, deformable droplets cannot be efficiently controlled by inertia-driven approaches. Here, we report a study on the lateral migration of dual droplet trains in a double spiral microchannel at low Reynolds numbers. The dominant driving mechanism is elucidated as wall effect originated from the droplet deformation. Three types of migration modes are observed with varying Reynolds numbers and the size-dependent mode is intensively investigated. We obtain empirical formulas by relating the migration to Reynolds numbers and droplet sizes. The effect of droplet deformability on the migration and the detailed migration behavior along the double spiral channel are discussed. Numerical simulations are also performed and yielded in qualitative agreement with the experiments. could be a promising alternative to existing inertia-driven approaches bio-particles. This proposed low Re approach based on lateral migration especially concerning deformable entities and susceptible

螺旋微流道分级分离纳米纤维素

利用螺旋微流控芯片分级分离纳米纤维素,使纳米纤维素按长短依次分布在通道内,从而实现纳米纤维素的分级分离。研究了最小螺旋半径为5 mm,最大螺旋半径为15 mm,螺旋圈数分别为T=4和T=6的单、双螺旋微流控芯片在不同流速下对纳米纤维素分级分离效果的影响。结果表明:流速为80μL/min时为最佳分离流速,其中螺旋圈数为T=6的单螺旋微流控芯片的分级分离效果最佳。

L形截面螺旋微流道中微粒的惯性聚焦特性

研制了一种L形截面螺旋微流道结构的惯性微流控芯片,并基于数值模拟和实验测试的方法研究了粒径6μm的聚苯乙烯粒子在微流道中的惯性聚焦效应。通过分析粒子运动轨迹的荧光图谱和对应的荧光强度曲线,发现随着粒子溶液体积流量增加至200μL/min及以上时,绝大部分粒子逐渐聚焦至微流道内壁面附近的平衡位置,形成宽约18μm的粒子聚焦带。此外,发现该微流道存在800μL/min的体积流量阈值,当粒子溶液体积流量超过阈值时,部分粒子会聚焦至靠近微流道中心处的平衡位置,从而形成另一束宽约9μm的粒子聚焦带。进一步研究粒子的双聚焦平衡位置沿螺旋微流道长度的变化规律,发现起初两束粒子聚焦带分别位于内外两侧矩形微流道中,此后会随运动距离的增加逐渐变窄,并向微流道内侧迁移,尤其当粒子运动至流道第8圈时,外侧矩形微流道的粒子将被内侧强二次流漩涡逐步拖拽至内侧微流道中,并被束缚于内壁面附近。上述研究结论可为深入研究复杂结构微流道中粒子的惯性聚焦机理提供重要参考。