A numerical study of the Coriolis effect in centrifugal microfluidics with different channel arrangements

Abstract

The Coriolis force has been of great interest to control the transversal flow that is critical for mixing or switching fluids in centrifugal microfluidics. Therefore, the variation in the Coriolis effect has been extensively investigated by varying the rotational speeds and the cross-sectional geometry of microchannels. However, the subject of such investigations has been limited to radially positioned microchannels even though channels can lie everywhere on the rotating platform with different arrangements. In this study, we use numerical methods to investigate the Coriolis effect resulting from the angular alignment (AA) and radial displacement (RD) of rotating microchannels. Our analysis focuses on determining the contribution that different channel arrangements have in the deviation of parabolic velocity profiles, which is generally produced by the effective Coriolis force. We found that the flow can deviate even at a low rotational speed, where the Coriolis force is negligible, with an AA of up to 33 % which is a sufficient amount for flow switching. Once the rotational speed reaches to the critical RPM, the flow deviates by an effective Coriolis force, but the deviation systematically varies with AA or RD. As the Coriolis force becomes more dominant with a high rotational speed, the deviation reaches a saturation point, while flow rate is regulated by AA or RD, enabling the flow rate to remain low even at very high RPM, without reducing the deviation. The variation in the Coriolis effect due to the different channel arrangements investigated in this study is believed to provide an essential basis to design and develop centrifugal microfluidic systems.