Abstract
This paper conceptualizes and mathematically models a dielectrophoretic microdevice with planar corrugated electrodes for focusing micro-particles at any lateral location along the width of the micro-scale flow passage; two of these electrodes are placed on the top and bottom surfaces of the micro-scale flow passage with the electrodes on the top and bottom aligned with each other to form a pair. The mathematical model includes equations of motion, Navier-Stokes equations, and equations of electric voltage and field and considers the influence of several phenomena, including inertia, sedimentation, drag, virtual mass and dielectrophoresis on the focusing of micro-particles. The mathematical model is solved using the finite difference method. The mathematical model is used for parametric study, thereby revealing that the performance metrics related to focusing depend on the geometric (micro-scale flow passage and electrode dimensions) and operating (applied electric voltages and volumetric flow rate) parameters of the microdevice. The mathematical model allows for determining the operating and geometric parameters for achieving the desired performance metrics based on constraints. The mathematical model is validated using experimental data from the literature.
Highlights
Microfluidic devices employ flow passages smaller than 1 mm and exhibit several positive attributes, including minimal requirements of samples and reagents, high sensitivity and specificity, minimal consumption of power, small footprint, and portability
This work conceptualizes an electrode design and electrode configuration for employment in a microdevice to realize dielectrophoresis-enabled 3D focusing of microparticles; subsequently, a mathematical model is developed for studying the working of the microdevice employing the conceptualized electrode design
By keeping the applied voltages the same, it is possible to realize 3D focusing of micro-particles at the center of the microscale flow passage, and by keeping the applied voltages unequal, it is possible to realize 3D focusing of microparticles at positions other than the center of the micro-scale flow passage
Summary
Microfluidic devices employ flow passages smaller than 1 mm and exhibit several positive attributes, including minimal requirements of samples and reagents, high sensitivity and specificity, minimal consumption of power, small footprint, and portability. Kung et al [9] realized a microdevice with two continuous electrodes on each of the opposing surfaces in the vertical direction of the micro-scale flow passage for achieving 3D focusing at high throughput; all electrodes were independently controllable, which allowed for positioning microparticles at any desired location over the cross-section of the micro-scale flow passage. 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 This is the first work to propose the electrode design shown in Fig. 1 and to analyze the performance of the microdevice employing it. The mathematical model developed in this work is dynamic and allows for determining the transient behavior; knowledge of the transient behavior is required for estimating the length of the device
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