| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 105 === Recently, scientists reported that the flows resulting from the action of an applied electric field on its own induced charges around a polarizable structure as “induced-charged electro-osmosis” (ICEO), which is capable of driving Janus particle, whose surfaces have two or more distinct properties, under the electric fields by “induced-charge electrophoresis” (ICEP). However, the directly experimental data of particle velocity for ICEP and flow velocity for ICEO in orientation-dependency with respect to electric fields are seldom investigated by scientists. We achieve that the magnetic moment of superparamagnetic Janus particle can be manipulated by external magnetic fields, the polarization effect of Janus particles with different coating thickness experimentally measured in different orientation under the electric field.
In the case of Janus particles with thin metallic coating, the ICEP motion of particle mainly moves perpendicular to the electric field without magnetic. The ICEP velocity and ICEO flow of Janus particle in different directions are measured in magnetic field and clear orientation dependent velocities are observed. However, for a thick metallic coating, the ICEP motion is dramatically parallel to the electric field without magnetic field and different orientation-dependent velocities are observed. We proposed that the strength of induced dipole of a Janus particle, depending on the thickness of the metallic coating and orientation of a particle, dominates the behavior of ICEP. Finally, this study provide a programmable method to control the particle by a rotating magnetic and frequency adjustment.
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