Isomagnetophoresis for microfluidic sorting and analysis

Abstract

This thesis presents isomagnetophoresis for microfluidic particle sorting and analysis and successful discrimination results of the subtle difference in the magnetic susceptibility of the polymer particles. Since isomagnetophoresis is based on the conventional magnetophoretic platform, the reliable microfluidic device for magnetophoresis has been established employing the ferromagnetic microstructure. As a demonstration of the magnetophoretic platform, the magnetophoretic purification of single-walled carbon nanotubes (SWCNTs) was carried out in the microfluidic device resulting in about 99.0 % purity. The theoretical analysis model for isomagnetophoresis was defined combining the magnetophoretic velocity, the drag force by Stokes’ law and the fluidic velocity profile in laminar flows. The magnetic susceptibility gradient was generated in the microfluidic channel using gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) and D-glucose. In the experiment, the polystyrene (PS; 14.78±0.20 ??m in diameter), poly(methyl methacrylate) (PMMA; 15.00±0.77 ??m) and borosilicate (BS; 14.01±1.00 ??m) microspheres were sorted and analyzed, where the PS and PMMA particles have similar diamagnetic susceptibility that cannot be distinguished by conventional magnetophoresis. This platform can be applied to label-free discrimination of the biological cells and nanotubes.