Improvement of the Size-Selective Separation of Microbeads in a Curved Microchannel Using Particle Focusing

Abstract

The size-selective microfluidic separation of glass beads in a curved rectangular microchannel was fabricated in our previous work. In this study, we improve its separation performance and attempt an experimental visualization to examine the separation resolution. In the previous work, we found by visualization that the trajectory of 20 µm glass beads was influenced by their travelling path along a straight inlet channel. Using a forced sheath flow, a consistent bead trajectory along the middle of the straight inlet channel was obtained, and the sheath angle to minimize the focusing width of the flowing distributed beads was determined to be 45°. The physical explanation for the dynamic behavior of microbeads was elaborated. When the ratio of Stokes force to centrifugal force mainly acting on a glass bead fell under unity, the glass bead moved out to the wall in spite of the fact that its size was less than the height of the zero velocity position. To examine the separation resolution, the newly designed size-selective separation microchannel with the sheath was fabricated and its separation performance was visualized. The movement of the glass beads showed a good agreement with the separation mechanism explained by the force ratio. The resolution of the separation was visualized to be 10 µm for the size of glass beads used in the experiment. The size-selective separation performance was explained in terms of physical forces and was improved by solving the previous problems. A cascade device for the continuous separation of microbeads of various sizes can improve the separation resolution.

Performance Evaluation of Rotational Flow of a 2×2 Microfluidic Centrifuge with varying Inlet Conditions and Chamber Sizes

“…대표적인 분리 기술로는 회전 축을 중심으로 물질을 회전하여 발생하는 원심력을 이용 한 원심분리기 [1] , 전기장이나 자기장의 영향을 받아 하전 된 물질들이 유동성 매체 내에서 이동하는 전자기영동 [2] , 그리고 이동상과 고정상에 대한 혼합 성분의 인력 차이를 이용한 크로마토그래피 [3] [4] , 마 이크로 필러 구조물을 이용한 입자들의 거동의 차이를 이 용한 방법 [5] 과 마이크로 크기의 필터를 이용하여 입자를 분리하는 방법 [6] [7] . …”

Separation of Different Sized Nanoparticles with Time Using a Rotational Flow

“…To determine their cellular origin, size, and the contained biomaterials, various analytical tools such as capillary electrophoresis, 20) mass chromatography, 21) bead handling, 22) and centrifugation 23) have been used to enrich and isolate vesicles at lower concentrations in applications of biotechnology and medical science. Also, microfluidic approaches have been introduced to separate cells and particles suspended in a liquid by using the strong Dean flow obtained in a curved microchannel, 24,25) the pinched flow fractionation obtained in a nonuniform flow, 26) the deterministic lateral displacement generated in a pillar array, 27) and microfiltration. 28,29) Regardless of the potential of the microfluidic approaches to separate cellular vesicles, the successful separation of target vesicles in the range of smaller than 100 nm in size has rarely been reported.…”

Separation of different sized nanoparticles with time using a rotational flow in a 2×2 microfluidic centrifuge

“…Also, microfluidic approaches have been introduced to separate cells and particles suspended in a liquid by using the strong Dean flow [5,6] obtained in a curved microchannel, the pinched flow fractionation obtained in a nonuniform flow [7], the deterministic lateral displacement generated in a pillar array [8], and microfiltration [9,10].…”