Dimensional analysis and parametric studies of the microwell for particle trapping

Recently, the microwell has been widely used for cell trapping due to its simple design and enclosed microenvironment for on-chip cell culture and stimulation. In this paper, we investigated the effect of various geometrical factors on microwells for efficient particle analysis. We used the Arbitrary Lagrangian–Eulerian method to calculate the trajectory of particles entering circular and triangular microwells under various geometrical factors, particle size, and flow conditions. Our simulation results show that the W/L = 2 triangular microwell provides the best trapping efficiency due to a stronger recirculation vortex. A smaller particle size or slower flow rate also enhances particle trapping efficiency. To validate simulation results, we flowed 4.5, 6, and 10 µm diameter polystyrene beads into W/L = 1 circular, W/L = 1 and W/L = 2 triangular microwells under various flow rates. The experimental results agreed well with simulation results, showing that the occupancy of W/L = 2 triangular microwell was sevenfold and twofold higher than W/L = 1 circular and W/L = 1 triangular microwells, respectively. Overall, the above results can provide a useful guideline to design the microwell device for efficient hydrodynamic particle trapping, which can be applied to single cell analysis or rare cell capture.