DEP-on-a-Chip: Dielectrophoresis Applied to Microfluidic Platforms

Dielectric particles in a non-uniform electric field are subject to a force caused by a phenomenon called dielectrophoresis (DEP). DEP is a commonly used technique in microfluidics for particle or cell separation. In comparison with other separation methods, DEP has the unique advantage of being label-free, fast, and accurate. It has been widely applied in microfluidics for bio-molecular diagnostics and medical and polymer research. This review introduces the basic theory of DEP, its advantages compared with other separation methods, and its applications in recent years, in particular, focusing on the different electrode types integrated into microfluidic chips, fabrication techniques, and operation principles.

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Combination of Au Dielectrophoresis Chip and Optical Tweezers for Cell Culture

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.656-657.549 ◽

2015 ◽

Vol 656-657 ◽

pp. 549-553

Author(s):

Kyohei Nishimoto ◽

Kozo Taguchi

Keyword(s):

Electric Field ◽

Optical Tweezers ◽

Cell Separation ◽

Low Cost ◽

Three Dimensional ◽

Uniform Electric Field ◽

Objective Lens ◽

Separation System ◽

Ac Electric Field ◽

Viable Cells

Dielectrophoresis (DEP) force will arise when an inhomogeneous AC electric field with sinusoidal wave is applied to microelectrodes. By using DEP, we could distinguish between viable and non-viable cells by their movement through a non-uniform electric field. In this paper, we propose a yeast cell separation system, which utilizes an Au DEP chip and an optical tweezers. The Au DEP chip is planar quadrupole microelectrodes, which were fabricated by Au thin-film and a box cutter. This fabrication method is low cost and simpler than previous existing methods. The tip of the optical tweezers was fabricated by dynamic chemical etching in a mixture of hydrogen fluoride and toluene. The optical tweezers has the feature of high manipulation performance. That does not require objective lens for focusing light because the tip of optical tweezers has conical shape. By using both the Au DEP chip and optical tweezers, we could obtain three-dimensional manipulation of specific cells after viability separation.

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Induced-charge electroosmotic flow around dielectric particles in uniform electric field

Journal of Colloid and Interface Science ◽

10.1016/j.jcis.2013.08.017 ◽

2013 ◽

Vol 410 ◽

pp. 102-110 ◽

Cited By ~ 15

Author(s):

Fang Zhang ◽

Dongqing Li

Keyword(s):

Electric Field ◽

Electroosmotic Flow ◽

Uniform Electric Field ◽

Dielectric Particles ◽

Induced Charge

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Investigation into Normal Pressure during Electrorheological Fluid-Assisted Polishing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.503-504.119 ◽

2012 ◽

Vol 503-504 ◽

pp. 119-122

Author(s):

Yun Wei Zhao ◽

Lei Zhang ◽

Zhuo Yang

Keyword(s):

Electric Field ◽

Hydrodynamic Lubrication ◽

Normal Pressure ◽

Electrorheological Fluid ◽

Uniform Electric Field ◽

Tool Electrode ◽

Rigid Core ◽

Abrasive Particles ◽

Dielectric Particles ◽

Polishing Fluid

The normal pressure in polishing area is investigated in electrorheological (ER) fluid-assisted polishing process. Under the influence of the non-uniform electric field, the dielectric particles in the ER polishing fluid are polarized to form the rigid core attached to the tool electrode due to the ER effect. In this work, the rigid core generated by the gathered mass of ER polishing fluid on the tip of tool electrode with the applied electric field is analyzed. The material is removed by abrasive particles under the effect of normal pressure and velocity. Based on the theory of hydrodynamic lubrication, a mathematical model taking into account the normal pressure is derived. Further experiments about the normal pressure experiments changing with the applied voltage, spindle rotational speed and working gap are conducted and the experimental results are compared with the theoretical results, which confirm the validity of the presented model

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Dielectrophoretic Characterisation of Mammalian Cells above 100 MHz

Journal of Electrical Bioimpedance ◽

10.5617/jeb.196 ◽

2019 ◽

Vol 2 (1) ◽

pp. 64-71 ◽

Cited By ~ 21

Author(s):

Colin Chung ◽

Martin Waterfall ◽

Steve Pells ◽

Anoop Menachery ◽

Stewart Smith ◽

...

Keyword(s):

Dielectric Properties ◽

Cell Separation ◽

Mammalian Cells ◽

Uniform Electric Field ◽

Cell Diameter ◽

Label Free ◽

Myeloma Cells ◽

A Value ◽

A Cell

Abstract Dielectrophoresis (DEP) is a label-free technique for the characterization and manipulation of biological particles - such as cells, bacteria and viruses. Many studies have focused on the DEP cross-over frequency fxo1, where cells in a non-uniform electric field undergo a transition from negative to positive DEP. Determination of fxo1 provides a value for the membrane capacitance from the cell diameter, the means to monitor changes in cell morphology and viability, and the information required when devising DEP cell separation protocols. In this paper we describe the first systematic measurements of the second DEP cross-over frequency fxo2 that occurs at much higher frequencies. Theory indicates that fxo2 is sensitive to the internal dielectric properties of a cell, and our experiments on murine myeloma cells reveal that these properties exhibit temporal changes that are sensitive to both the osmolality and temperature of the cell suspending medium.

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Dielectrophoresis Prototypic Polystyrene Particle Synchronization toward Alive Keratinocyte Cells for Rapid Chronic Wound Healing

Sensors ◽

10.3390/s21093007 ◽

2021 ◽

Vol 21 (9) ◽

pp. 3007

Author(s):

Revathy Deivasigamani ◽

Nur Nasyifa Mohd Maidin ◽

M. F. Mohd Razip Wee ◽

Mohd Ambri Mohamed ◽

Muhamad Ramdzan Buyong

Keyword(s):

Wound Healing ◽

Electric Field ◽

Electric Fields ◽

Chronic Wounds ◽

Particle Trajectory ◽

Uniform Electric Field ◽

Fibroblast Cells ◽

Label Free ◽

Conductive Medium ◽

Drag Forces

Diabetes patients are at risk of having chronic wounds, which would take months to years to resolve naturally. Chronic wounds can be countered using the electrical stimulation technique (EST) by dielectrophoresis (DEP), which is label-free, highly sensitive, and selective for particle trajectory. In this study, we focus on the validation of polystyrene particles of 3.2 and 4.8 μm to predict the behavior of keratinocytes to estimate their crossover frequency (fXO) using the DEP force (FDEP) for particle manipulation. MyDEP is a piece of java-based stand-alone software used to consider the dielectric particle response to AC electric fields and analyzes the electrical properties of biological cells. The prototypic 3.2 and 4.8 μm polystyrene particles have fXO values from MyDEP of 425.02 and 275.37 kHz, respectively. Fibroblast cells were also subjected to numerical analysis because the interaction of keratinocytes and fibroblast cells is essential for wound healing. Consequently, the predicted fXO from the MyDEP plot for keratinocyte and fibroblast cells are 510.53 and 28.10 MHz, respectively. The finite element method (FEM) is utilized to compute the electric field intensity and particle trajectory based on DEP and drag forces. Moreover, the particle trajectories are quantified in a high and low conductive medium. To justify the simulation, further DEP experiments are carried out by applying a non-uniform electric field to a mixture of different sizes of polystyrene particles and keratinocyte cells, and these results are well agreed. The alive keratinocyte cells exhibit NDEP force in a highly conductive medium from 100 kHz to 25 MHz. 2D/3D motion analysis software (DIPP-MotionV) can also perform image analysis of keratinocyte cells and evaluate the average speed, acceleration, and trajectory position. The resultant NDEP force can align the keratinocyte cells in the wound site upon suitable applied frequency. Thus, MyDEP estimates the Clausius–Mossotti factors (CMF), FEM computes the cell trajectory, and the experimental results of prototypic polystyrene particles are well correlated and provide an optimistic response towards keratinocyte cells for rapid wound healing applications.

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