Ranjan Shashi, Zeming Kerwin Kwek, Jureen Roland, Fisher Dale, Zhang Yong
Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576.
Lab Chip. 2014 Nov 7;14(21):4250-62. doi: 10.1039/c4lc00578c.
Particle sorting methods in microfluidic platforms are gaining momentum for various biomedical applications. Bioparticles are found in different shapes and sizes. However, conventional separation techniques are mainly designed for separation of spherical particles. Thus, there is a need to develop new methods for effective separation of spherical and non-spherical bioparticles for various applications. Deterministic lateral displacement (DLD) microfluidic methods have become popular for high separation resolution, simplicity, and predictability. However, shape sorting in the DLD separation methods is not well researched. Recently, we explored this area and found that pillar shapes in DLD significantly affect bioparticle separation. In this work, we designed a group of different pillar shapes with protrusions and groove structures with the hypothesis that pillar protrusions will induce particle rotation while pillar grooves will confine the particle rotational movement in a directed path for effective separation in a DLD pillar array. Using combinations of protrusions and grooves, 3-dimensional spherical particles, 2-dimensional planar disc-shaped red blood cells and 1-dimensional rod-shaped bacteria were separated and two interesting phenomena were observed. Firstly, the arrangement of pillar protrusions and grooves induces inertial movements, enhancing the separation of spherical particles. Secondly, non-spherical particles experience dominant rotational movements due to the protrusions and grooves which help in changing their orientations. This gives an opportunity to perform efficient separation based on the desired orientation (the longest dimension of the particles) by restricting or containing their movement within a specific DLD path.
微流控平台中的粒子分选方法在各种生物医学应用中越来越受到关注。生物粒子具有不同的形状和大小。然而，传统的分离技术主要是为分离球形粒子而设计的。因此，需要开发新的方法来有效分离球形和非球形生物粒子以用于各种应用。确定性侧向位移（DLD）微流控方法因其高分离分辨率、简单性和可预测性而受到欢迎。然而，DLD分离方法中的形状分选研究并不充分。最近，我们探索了这一领域，发现DLD中的柱形对生物粒子分离有显著影响。在这项工作中，我们设计了一组具有凸起和凹槽结构的不同柱形，假设柱形凸起会诱导粒子旋转，而柱形凹槽会将粒子的旋转运动限制在一条定向路径上，以便在DLD柱阵列中进行有效分离。通过结合使用凸起和凹槽，对三维球形粒子、二维平面盘状红细胞和一维杆状细菌进行了分离，并观察到了两个有趣的现象。首先，柱形凸起和凹槽的排列会诱导惯性运动，增强球形粒子的分离效果。其次，非球形粒子由于凸起和凹槽而经历主导的旋转运动，这有助于改变它们的方向。这提供了一个机会，通过在特定的DLD路径内限制或控制它们的运动，基于所需的方向（粒子的最长尺寸）进行高效分离。
