Modeling and Simulation of Dielectrophoretic Particle Assembly

Volume 7: Fluids and Heat Transfer, Parts A, B, C, and D ◽

10.1115/imece2012-85768 ◽

2012 ◽

Author(s):

Mohammad Robiul Hossan ◽

Prashanta Dutta

Keyword(s):

Electric Field ◽

Stress Tensor ◽

Immersed Boundary Method ◽

Applied Electric Field ◽

Immersed Boundary ◽

Particle Assembly ◽

Immersed Interface ◽

Boundary Method ◽

Fluid Media ◽

A Chain

In this paper, we present a comprehensive study of dielectrophoretic particle assembly using hybrid immersed interface-immersed boundary method where both dielectrophoretic and hydrodynamic forces are evaluated with interface resolved approach instead of point-particle method. Immersed interface method is employed to capture physics of electrostatics in a fluid media with embedded particles, while immersed boundary method is used to study hydrodynamics with rigid and/or flexible immersed boundaries. Unlike existing studies, dielectrophoretic force is obtained using Maxwell’s stress tensor; a comparative study between Maxwell stress tensor and effective dipole moment methods are presented. This hybrid method is employed to demonstrate the dielectrophoretic particle assembly for both similar and dissimilar particles. In a fluid media, the similar particles form a chain parallel to the applied electric field, while the dissimilar particles form a chain perpendicular to the applied electric field. These results are consistent with the recent experimental observations.

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Numerical Investigation of DC Dielectrophoretic Particle Transport

Volume 2, Fora: Cavitation and Multiphase Flow; Fluid Measurements and Instrumentation; Microfluidics; Multiphase Flows: Work in Progress; Fluid-Particle Interactions in Turbulence ◽

10.1115/fedsm2014-21674 ◽

2014 ◽

Cited By ~ 2

Author(s):

Mohammad Robiul Hossan ◽

Prashanta Dutta ◽

Robert Dillon

Keyword(s):

Electric Field ◽

Immersed Boundary Method ◽

Particle Transport ◽

Suspended Particles ◽

Immersed Boundary ◽

Immersed Interface Method ◽

Particle Assembly ◽

Immersed Interface ◽

Boundary Method ◽

Fluid Media

In this paper, we investigate the mechanism of two dimensional DC dielectrophoresis (DEP) using a hybrid immersed interface-immersed boundary method where both electric and hydrodynamic forces are obtained with interface-resolved approach instead of point-particle method. Immersed interface method is employed to predict DC electric field in a fluid media with suspended particles while immersed boundary method is used to study particle transport in a fluid media. The Maxwell stress tensor approach is adopted to obtain dielectrophoretic force. This hybrid numerical scheme demonstrates the underlying physics of positive and negative dielectrophoresis, and explains their contribution in particle assembly with consideration of size, initial configurations and electrical properties of particles as well as fluid media. The results show that the positive DEP provides accelerating motion while negative DEP provides decelerating motion depending on the electrode configurations and initial particle positions. The results also show that the local nonuniformity in electric field induced by the suspended particles guides the particles to form stable chain. Both positive and negative DEP can contribute in the process of particle assembly formation based on the properties of particles and fluid media. This hybrid immersed interface-immersed boundary scheme could be an efficient numerical tool for understanding fundamental mechanism of dielectrophoresis as well as designing and optimization of DEP based microfluidic devices.

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Dielectrophoretic Interactions and Chaining of Ellipsoidal Particles in a Microchannel

Volume 7: Fluids Engineering ◽

10.1115/imece2016-67247 ◽

2016 ◽

Author(s):

Mohammad Robiul Hossan ◽

Partha P. Gopmandal ◽

Prashanta Dutta ◽

Robert Dillon

Keyword(s):

Electric Field ◽

Stress Tensor ◽

Applied Electric Field ◽

Immersed Boundary ◽

Immersed Interface Method ◽

Immersed Interface ◽

Ellipsoidal Particles ◽

Clockwise Direction ◽

A Chain ◽

Final Orientation

Recent experimental studies report that the understanding of dielectrophoretic (DEP) interactions and chaining of irregularly shaped particles, particularly ellipsoidal shaped particle, are critical for development of smart materials, engineered biological cellular structure and tissue formation. This paper presents a comprehensive numerical investigation of direct current (DC) dielectrophoretic (DEP) chaining and interactions of ellipsoidal particles in a microchannel. A hybrid immersed boundary-immersed interface method is employed to explain the fundamental mechanism of DEP interactions and chaining of ellipsoidal particles. Electric field equations are solved by the immersed interface method while the immersed boundary method is employed to solve fluid equations. The DEP force was estimated by using Maxwell’s stress tensor (MST) and the Cauchy stress tensor (CST) was employed to evaluate hydrodynamic force. The results show that the electrical properties of fluid and particles are the main deciding factor on the final orientation of ellipsoidal particles. However the size, shapes and initial positions and orientations have significant impact on interaction time spans. Results also show that if the interacting particles are electrically similar i.e. having same electrical conductivity then they always form a chain parallel to the applied electric field, otherwise they form a chain which is orthogonal to the applied electric field. In parallel chaining, particles rotate in a clockwise direction, while in orthogonal (to the applied electric field) chaining, particles rotate in counter-clockwise direction to reach to the final orientation. Results also indicate that the ellipsoidal particles go through an electro-orientation process if initially the major axis of the ellipsoidal particles is not in perfect alignment with the applied electric field. The electro-orientation and DEP interaction take place simultaneously to reach to final stable orientation. This study provides critical insight on the mechanism of DEP interactions and chaining of ellipsoidal shaped particles.

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