Electromagnetophoretic migration velocity of organic microdroplets with surfactants using permanent magnets.

By using the electromagnetophoretic migration technique with permanent magnets, the electromagnetophoretic migration velocimetry in a droplet-based system was demonstrated for organic droplets dispersed in an aqueous solution. Migration of 2-fluorotoluene droplets with a diameter of 8 - 16 μm dispersed in 1.0 M KCl aqueous solution could be achieved in the same manner as for solid particles. The effect of cetyltrimethylammonium bromide (CTAB) on the electromagnetophoretic migration velocity of the droplets was also investigated. When the concentration of CTAB was in the range from 10(-6) to 10(-4) M, the electromagnetophoretic migration velocity of 2-fluorotoluene droplets decreased as the concentration of CTAB increased. With this measurement, we could successfully characterize organic droplets in terms of the amount of adsorbing surfactants by evaluating the surface conductivity of organic droplets calculated based on their electromagnetophoretic migration velocity.