Separation of fine particles and liquid using a physical trapping method via a stepped structure.

This study investigated a component separation method using a microfluidic device. Specifically, we integrated a micron-scale stepped structure, which is a component of a microfluidic device, into the channel of this system. The stepped structure trapped fine particles, and we successfully separated the particles from the liquid components. The constriction component for trapping fine particles was realized in the vertical direction instead of the planar direction. This structure was formed in the vertical direction for two main reasons. First, it is easier to fabricate a constriction width of approximately 1 μm in the height direction than in the plane direction. Second, the trapping efficiency per unit area of the chip may be increased using this orientation. Using versatile soft lithography, we developed a microfluidic device that satisfies the required design specifications. However, the hardness of polydimethylsiloxane (PDMS) must be adjusted such that it can efficiently trap fine particles. We succeeded in trapping more than 99.9% of polystyrene particles with a diameter of 10 μm when using the developed hard PDMS device. The proposed system is particularly effective for liquid-component extraction, such as extracting only plasma from blood. [ABSTRACT FROM AUTHOR]