Analysis and experiment of transient filling flow into a rectangular microchannel on a rotating disk

In order to predict the time-dependent behaviors of the moving front in lab-on-a-CD systems or centrifugal pumping, an analytical expression and experimental methods of centrifugal-force-driven transient filling flow into a rectangular microchannel in centrifugal microfluidics are presented in this paper. Considering the effect of surface tension, and neglecting the effect of Coriolis force, the velocity profile, flow rate, the moving front displacement and the pressure distribution along the microchannel are characterized. Experiments are carried out using the image-capturing unit to measure the shift of the flow in rectangular microchannels. The flow characteristics in rectangular microchannels with different cross-sectional dimensions (200, 300 and 400 μm in width and 140, 240 and 300 μm in depth) and length (18 and 25 mm) under different rotational speed are investigated. According to the experimental data, the model can be more reasonable to predict the flow displacement with time, and the errors between theoretical and the experimental will decrease with increasing the cross-section size of the microchannel.