A microfluidic magnetophoresis chip for continuous single-walled carbon nanotube purification from magnetic force-induced superparamagnetic metal catalyst

We present a continuous magnetophoretic purification method of single-walled carbon nanotubes (SWCNTs) from superparamagnetic Fe catalyst nanoparticles using the enhanced magnetic force in a microfluidic device. The iron impurities of SWCNT were deflected to the higher magnetic energy region in the microfluidic channels where magnetic field was asymmetrically generated in perpendicular direction to the streamline. We carried out continuous purification at a flow rate of 0.36 mg of as-received SWCNTs per hour. The estimated purity of the purified SWCNTs was over 99.0 % when as-received SWCNTs containing about 18.14 % of iron catalysts were used by single-round purification.