No abstract

A simpli ed electric eld calculation is used to reveal several unique characteristics of the dielectrophoretic force to capture particles using electrodes on which conductive aligned micropillars are placed. This electrode con guration is a model to investigate a previous report about dielectrophoretic particle capture using an electrode on which carbon nanotubes have been synthesized. Conventionally, it has been believed that dielectrophoresis tends to capture larger particles because the dielectrophoretic force increases with increasing particle size when ordinal electrodes are used. However, when an electrode con guration with aligned conductive micropillars is used, small particles with diameters that are comparable to those of the micropillars can be selectively captured by dielectrophoresis. Accordingly, the size of the particles that need to be collected can be controlled by choosing an appropriate micropillar diameter. For relatively large particles, micropillars with a larger diameter can generate a stronger dielectrophoretic force over a larger area, such that a larger amount of particles can be collected. The number density of the micropillars was shown to negatively a ect the dielectrophoretic force. The information obtained in this work will be useful for designing new DEP particle separators for size-selective particle capture. The use of controlled synthesis of CNTs is proposed to realize the fabrication of the electrode con guration modeled here.

Visualization of a streak line pattern in a mixing vessel is quite useful for understanding the mixing mechanism and designing an optimal mixing vessel. However, conventional experimental methods for visualizing streak lines require a lot of time to construct impellers and prepare solutions. Although various commercial fluid analysis software has been developed, there are still no examples of its use for calculating streak lines in mixing vessels. A simulation method was developed to quickly evaluate the streak line pattern in a laminar mixing vessel by numerical analysis with commercial code. A commercial CFD code can calculate streak line patterns in a laminar mixing vessel. It was found that a lattice method was more suitable than a particle method for the simulation of the streak line.