Eluru Gangadhar, Nagendra Pavan, Gorthi Sai Siva
Optics and Microfluidics Instrumentation Lab, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India.
Micromachines (Basel). 2019 Jul 15;10(7):471. doi: 10.3390/mi10070471.
Separating the particles from the liquid component of sample solutions is important for several microfluidic-based sample preparations and/or sample handling techniques, such as plasma separation from whole blood, sheath-free flow focusing, particle enrichment etc. This paper presents a microfluidic in-flow decantation technique that provides the separation of particles from particle-free fluid while in-flow. The design involves the expansion of sample fluid channel in lateral and depth directions, thereby producing a particle-free layer towards the walls of the channel, followed by gradual extraction of this particle-free fluid through a series of tiny openings located towards one-end of the depth-direction. The latter part of this design is quite crucial in the functionality of this decantation technique and is based on the principle called wee-extraction. The design, theory, and simulations were presented to explain the principle-of-operation. To demonstrate the proof-of-principle, the experimental characterization was performed on beads, platelets, and blood samples at various hematocrits (2.5%-45%). The experiments revealed clog-free separation of particle-free fluid for at least an hour of operation of the device and demonstrated purities close to 100% and yields as high as 14%. The avenues to improve the yield are discussed along with several potential applications.
对于几种基于微流体的样品制备和/或样品处理技术而言，将颗粒与样品溶液的液体成分分离至关重要，例如从全血中分离血浆、无鞘流聚焦、颗粒富集等。本文介绍了一种微流体内倾析技术，该技术可在流体流动过程中实现颗粒与无颗粒流体的分离。该设计包括在横向和深度方向上扩展样品流体通道，从而在通道壁处产生一个无颗粒层，然后通过位于深度方向一端的一系列微小开口逐渐提取该无颗粒流体。该设计的后一部分对于这种倾析技术的功能至关重要，并且基于所谓的微量提取原理。文中介绍了该设计、理论和模拟，以解释其工作原理。为了证明原理的可行性，对不同血细胞比容（2.5%-45%）的珠子、血小板和血液样本进行了实验表征。实验表明，该装置至少运行一小时可实现无颗粒流体的无堵塞分离，纯度接近100%，产率高达14%。文中讨论了提高产率的途径以及几种潜在应用。
