Dielectrophoresis Multipath Focusing of Microparticles through Perforated Electrodes in Microfluidic Channels

Abstract

This paper presents focusing of microparticles in multiple paths within the direction of the flow using dielectrophoresis. The focusing of microparticles is realized through partially perforated electrodes within the microchannel. A continuous electrode on the top surface of the microchannel is considered, while the bottom side is made of a circular meshed perforated electrode. For the mathematical model of this microfluidic channel, inertia, buoyancy, drag and dielectrophoretic forces are brought up in the motion equation of the microparticles. The dielectrophoretic force is accounted for through a finite element discretization taking into account the perforated 3D geometry within the microchannel. An ordinary differential equation is solved to track the trajectories of the microparticles. For the case of continuous electrodes using the same mathematical model, the numerical simulation shows a very good agreement with the experiments, and this confirms the validation of focusing of microparticles within the proposed perforated electrode microchannel. Microparticles of silicon dioxide and polystyrene are used for this analysis. Their initial positions and radius, the Reynolds number, and the radius of the pore in perforated electrodes mainly conduct microparticles trajectories. Moreover, the radius of the pore of perforated electrode is the dominant factor in the steady state levitation height.

Microdevice With Planar Corrugated Electrodes for Dielectrophoretic Focusing of Micro-Particles

“…Once the different components of the electric field are determined, the gradient of the square of the magnitude of the electric field can be determined for the purposes of calculating the DEP force. The gradient of the square of the electric field is numerically determined as shown in (12). A central difference scheme (2 nd order) is used to determine this parameter for all nodes except those on the faces in each direction.…”

“…Alnaimat et al [10,11] modeled AC-DEP-based microdevices for 3D focusing of micro-particles at any location in the direction of the width of the micro-scale flow passage; Alnaimat et al [10] employed several finite-sized IDT planar electrodes placed on the micro-scale flow passage on either side, while Alnaimat et al [11] employed two sets of planar electrodes placed on the micro-scale flow passage on either side. Alazzam et al [12] conceptualized a dielectrophoretic microdevice employing a continuous electrode on the microscale flow passage's upper and lower surfaces for 3D focusing micro-particles simultaneously at multiple locations in the direction of the width of the micro-scale flow passage; the lower electrode has perforations. Krishna et al [13] modeled 3D focusing in a dielectrophoretic microdevice using planar right-triangular electrodes located on the microscale flow passage's upper and lower surfaces.…”