Comprehensive analysis of particle motion under non-uniform AC electric fields in a microchannel

Abstract

AC electrokinetics is rapidly becoming a foundational tool for lab-on-a-chip systems due to its versatility and the simplicity of the components capable of generating them. Predicting the behavior of fluids and particles under non-uniform AC electric fields is important for the design of next generation devices. Though there are several important phenomena that contribute to the overall behavior of particles and fluids, current predictive techniques consider special conditions where only a single phenomenon may be considered. We report a 2D numerical simulation, using COMSOL Multiphysics, which incorporates the three major AC electrokinetic phenomena (dielectrophoresis, AC electroosmosis and electrothermal effect) and is valid for a wide range of operational conditions. Corroboration has been performed using experimental conditions that mimic those of the simulation and shows good qualitative agreement. Furthermore, a broad range of experiments has been performed using four of the most widely reported devices under varying conditions in order to show their behavior as it relates to the simulation. The large number of experimental conditions reported, together with the comprehensive numerical simulation, will help provide guidelines for scientists and engineers interested in incorporating AC electrokinetics into their lab-on-a-chip systems.

A capillary dielectrophoretic chip for real-time blood cell separation from a drop of whole blood

“…ACETF induces the fluid flow because of the joule heating of the fluid produces a temperature gradient in the conductivity solution, 46 which must be manipulated in the high conductivity solution (>0.1 S/m) and high frequency ($MHz). 32,[35][36][37][38]47 Too high temperature can cause the blood cells breach and produce the phenomenon of hemolysis. Therefore, we were operated in the low-frequency (100 kHz) and the appropriate voltage to reduce the electrothermal effect and achieve micro mixed effect.…”

“…Regarding the drawbacks of hydrodynamic technologies, electrokinetic techniques have demonstrated greater possibilities of meeting the requirements of in situ small-volume separation. There are numerous studies on electrophoresis (EP), 30 AC electro-osmosis (ACEO), 31,32 dielectrophoresis (DEP), 19,[23][24][25]33,34 and AC electrothermal flow (ACETF) 31,32,35-38 regarding bio-particle manipulation. One electrokinetic technology, DEP, has been widely used for manipulating, separating, 33,39 focusing, 40 and concentrating 41 cells/ bacteria/DNA in microfluidic channels.…”

Improving the binding efficiency of quartz crystal microbalance biosensors by applying the electrothermal effect

“…Moreover, the crossover frequency of the buffer solution used in this study (conductivity r ¼ 1.45 S=m) was approximately 1.1 GHz. 17 The conductivity and frequency (10 MHz) used in this study are both considerably high, hence the ACEO is neglected. 24,25 Parts of previous studies [26][27][28][29][30][31][32] adopted numerical models to verify the feasibility of using electrokinetic in developing flow field-based mixing sensors.…”

“…16 The three main AC electrokinetic phenomena are dielectrophoresis (DEP), AC electroosmosis (ACEO), and electrothermal effect (ETE). 17 Dielectrophoresis often involves microparticles such as cells 18 or bacteria. 19 However, dielectrophoresis may be ineffective for examining experimental specimens, which are often nanosize antibodies (proteins) or drug molecules.…”

Microfluidic concentration of bacteria by on-chip electrophoresis

“…In addition, high fields induce disturbing effects such as electrothermal flow and AC electroosmosis. 22,31,32 Bacteria and viruses exhibit a negative charge at physiological pH values. Therefore, electrophoretic concentration has the advantage to be universally applicable for a wide range of pathogens.…”