Characteristics of Aligned Micropillar Electrodes for Size-Selective Particle Capture by Dielectrophoresis: A Model of Dielectrophoresis Using Carbon Nanotube Electrodes

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.

A review of dielectrophoretic separation and classification of non‐biological particles

“…[76,77] used carbon nanotubes (CNT) that act as nanoelectrodes and enhance the local . The concept was theoretically discussed for the separation of nanometer particles by size [77] and experimentally demonstrated [76] for the separation of 10–20 nm TiO 2 (experiencing pDEP) from SiO 2 (experiencing nDEP) in ethanol. CNTs with 10–20 nm diameter (thus of the same size as target particles) were directly synthesized on two flat stainless‐steel electrodes at 3 mm distance (Fig.…”

“…In a series of papers, Sano, Tamon, and co-workers developed and applied a mesh-stacked DEP separator that was operated batch-wise. It was, according to the authors, suitable for large-scale separation [14,[76][77][78][79]. This consisted of multiple aligned sheets of stainless-steel wire meshes (aperture 0.5 mm, wire diameter 0.29 mm).…”