Numerical and experimental study of different geometries of expansion-contraction microchannels in particle sorting

In this paper, a new simulation method (quasi-three-dimensional) is introduced to model devices based on inertial and Magnus forces. Simulations were computed using the COMSOL software. The experiments were performed using micro channels made by lithography method out of PDMS and glass slides. The use of quasi-three-dimensional simulation method made the simulation time much shorter. Results showed with increasing the particle diameter and the flow Reynolds number in microchannels, particles reach their equilibrium positions faster and with changing aspect ratio of channel, equilibrium position of particles changed and different steady state patterns were observed. In expansion-contraction channels, increasing the particle diameter also increases the channel efficiency. But increasing the flow rate to reach its optimum of 3.5ml/min enhances the efficiency and then, increasing flow rate beyond it, would not have a positive effect on efficiency anymore. Also with changing geometry of expansion section from rectangle to circle, the capture efficiency reached 0.86. Experimental results also confirm the accuracy of the simulation results and 19 micrometer particles are trapped in the wide part of the channel and 10 micrometer particles come out of it.