Method for separating micron-sized particles using submillimetre-scale structures

Abstract This study presents a method for separating and recovering micron-sized objects using microfluidic devices, belonging to the passive group that utilises flow. The method proposed in this study utilises submillimetre-scale structures within the microfluidic device, thereby eliminating the need for high-precision microfabrication. Furthermore, the use of slow flow conditions distinguishes this approach from many previous studies. The objective of this research was to successfully separate particles with diameters ranging from 1 to 20 μm. By optimising the flow rate conditions, 100% separation was achieved for particles with diameters of 6.00 and 10.0 μm, and 96.9% for particles with a diameter of 20.0 μm. These results compare favourably with, or exceed, those reported in previous studies where passive methods were used for cell separation. Moreover, the technique effectively avoids the issues of viscosity and clogging that are inherent to separation methods based on conventional pillar and filter structures. By selecting the optimal flow rate, we were also able to isolate particles with a diameter of 1.00 μm. Thus, this method could serve as a technically viable alternative to centrifugation, which is commonly used as a pre-processing step for blood tests. The proposed method is well-suited for applications such as the aforementioned test, where particles larger than a specified size are trapped from a suspension containing multiple particle sizes and smaller particle sizes are recovered from the outlet well.