Magnetophoretic Continuous Purification of Single‐Walled Carbon Nanotubes from Catalytic Impurities in a Microfluidic Device

Abstract A magnetophoretic continuous purification method is presented of single‐walled carbon nanotubes (SWCNTs) from the superparamagnetic iron‐catalyst impurities in a microfluidic device without any influence on inherent SWCNT properties. By employing microfluidics and a magnetic‐field‐induced saw‐tooth nickel microstructure, a highly enhanced magnetic force in adjoining microchannels is exploited. The iron impurities of SWCNTs are attracted towards areas of higher magnetic‐flux density in the microchannels where magnetic field was asymmetrically generated perpendicularly to the streamline. We obtained highly purified SWCNTs at a rate of 0.36 mg h⁻¹ and that are estimated to be about 99 % purity.