Size-based microparticle seperation using negative magnetophoresis

Abstract

We present a new size-based microparticle separation device using negative magnetophoresis. Microparticles spiked in the paramagnetic medium were filtered with respect to their sizes in a microfluidic channel placed between two magnets. Negative magnetophoresis allows large microparticles to be captured before the magnets, while small microparticles pass through the magnets under a constant flow. With this method, we reached 84.2% capturing efficiency of large microparticles (44 µm diameter) and capturing purity of 80.3% in the presence of small microparticles (17 µm diameter) at 3 µL/min flow rate. The capturing purity could further improve up to 99% by increasing the flow rate.