Multi-Vortex Regulation for Efficient Fluid and Particle Manipulation in Ultra-Low Aspect Ratio Curved Microchannels

Abstract

Inertial microfluidics enables fluid and particle manipulation for biomedical and clinical applications. Herein, we developed a simple semicircular microchannel with an ultra-low aspect ratio to interrogate the unique formations of the helical vortex and Dean vortex by introducing order micro-obstacles. The purposeful and powerful regulation of dimensional confinement in the microchannel achieved significantly improved fluid mixing effects and fluid and particle manipulation in a high-throughput, highly efficient and easy-to-use way. Together, the results offer insights into the geometry-induced multi-vortex mechanism, which may contribute to simple, passive, continuous operations for biochemical and clinical applications, such as the detection and isolation of circulating tumor cells for cancer diagnostics.

High-Throughput Blood Plasma Extraction in a Dimension-Confined Double-Spiral Channel

“…Here, a represents the cell diameter, while H denotes the channel height. , Remarkably, despite the total length of the chip along the x -axis extending up to 21.5 cm, it occupies only a small device footprint of roughly 1.2 cm 2 (Figure S2). The distinctive double-spiral configuration possesses two primary advantages: it effectively minimizes the overall footprint of the chip and simultaneously ensures that particles or cells can traverse an adequate channel length to establish a stable focusing state. ,, The introduction of a small R and strategically placed micro-obstacles in the DD-channel can facilitate the stabilization and acceleration of secondary flows. − This strategy helps produce a significant strengthening of secondary flow for improving inertial focusing by circumventing excessive variations of R within conventional spiral channels. , …”

“…This reduction in U y adversely affects the ability to maintain a stable focus of particles within the channel. However, although the R of each loop in the DD-channel is also distinct, the curvature alteration caused by microstructure is the primary factor in the varying loops. ,− Given that each microstructure in the chip has the same size, their curvature values are also equal. Moreover, the alteration in curvature radius ( R = 150 μm) caused by microstructures is much smaller than that caused by the curvature radius ( R = 500–5300 μm) of the loops in the DD-channel.…”

Spiral Large-Dimension Microfluidic Channel for Flow-Rate- and Particle-Size-Insensitive Focusing by the Stabilization and Acceleration of Secondary Flow

“…The absence of comprehensive and efficient methods for stabilizing the Dean secondary flow leads to restricted ranges both in particle sizes and operational flow rates in achieving inertial focusing . Besides, owing to the larger channel dimensions (width: >600 μm, height: >80 μm), which lead to a weaker Dean secondary flow that hinders the rapid transverse movement and effective concentration of particles, the current spiral channels are usually of a smaller size. − This, in turn, limits the improvement of sample processing throughput. , Therefore, developing an innovative spiral microchannel that could stabilize and accelerate the secondary flow in large-dimension channels is still an imperative and challenging task in inertial microfluidic area.…”

Flow-Rate-Insensitive Plasma Extraction by the Stabilization and Acceleration of Secondary Flow in the Ultralow Aspect Ratio Spiral Channel

“…This novel approach marks a significant breakthrough in the field of cell separation as it helps release the constraints of channel dimension and offers new possibilities for optimizing the sorting process. However, the inconsistent secondary flow caused by variations in loop radius poses a significant obstacle to the successful formation of a spiral channel capable of efficiently concentrating cells. − Due to the lack of comprehensive and effective techniques for stabilizing the Dean flow, there are limitations in terms of inertial focusing on both particle sizes and operational flow rates. − Our group initially proposed a system with the aim of achieving efficient particle manipulation in a spiral channel with orderly arranged micro-obstacles. ,, This system was then further developed by Wang et al , to effectively realize single-cell focusing and sorting of circulating tumor markers. However, due to the size design of the channels, these structures are not able to allow for highly effective separation of various-sized blood cells, especially platelets.…”