Particles sorting in micro-channel system utilizing magnetic tweezers and optical tweezers

This study evaluates a method for separating magnetic microparticles in a micro channel by using embedded inverted-laser tweezers, a microflow pump, and a micro magnet. Various particles were separated using optical and/or magnetic tweezers, and were identified and counted to determine the dependence of the sorting rate on the channel flow velocity. The particle sorting experiment showed good separation results when the designed channel and magnetic tweezers were used. For magnetic particles, lower flow velocities corresponded to larger separating rates with a maximum separating rate of 81%. When the designed channel and optical tweezers were used, the polystyrene particle separating rate was as high as 94%. When both the optical tweezers and the magnetic tweezers were used, the optical tweezers were more effective in trapping polystyrene particles with flow velocities between 0.09 and 0.25 μm/s. For flow velocities between 0.09 and 0.17 μm/s, the separating rate for polystyrene particles reached 95% and the separating rate for magnetic particles reached 85%. This hybrid system can be applied to the separation of various particles in unknown mixtures.

► We proposed a method for separating magnetic microparticles using optical and magnetic tweezers.
► Using designed channel and magnetic tweezers, the maximum magnetic particle separating rate was 81%.
► Using designed channel and optical tweezers, the largest polystyrene particle separating rate was 94%.
► When two tweezers were used, the separating rates of polystyrene and magnetic particles were 95% and 85%.