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ABSTRACT Dielectrophoresis (DEP) has been extensively researched over the years for filtration, separation, detection, and collection of micro/nano/bioparticles. Numerical models have historically been employed to predict particle trajectories in three‐dimensional (3D) DEP systems, but a common issue arises due to inherent noise near the edges of electrodes due to electric potential discontinuity, specifically when calculating electric field and gradient of electric field‐squared, . This noise can be reduced to a certain extent with a finer mesh density but results near the electrode edge still have significant error. Realizing the importance of particle‐electrode edge interactions prevalent in positive DEP systems, analytical solutions given by Sun et al. was incorporated to demonstrate an improved 3D model of interdigitated electrodes. The results of electric field and gradient of electric field‐squared of the numerical model and the improved analytical 3D model were compared, within a simulation space of 50 µm height, 10 µm width, and 50 µm length with interdigitated electrodes of the same width and gap of 10 µm. The DEP particle trajectory error due to the noise was quantified for different particle sizes at various heights above the electrode edge. For example, at 5 Vrms, a trapped 500 nm particles exhibited a velocity error of 104µm/s (it should have been zero).
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Electrokinetic particle trapping in microfluidic wells using conductive nanofiber mats
Abstract The frequency dependence of electrokinetic particle trapping using large‐area (>mm2) conductive carbon nanofiber (CNF) mat electrodes is investigated. The fibers provide nanoscale geometric features for the generation of high electric field gradients, which is necessary for particle trapping via dielectrophoresis (DEP). A device was fabricated with an array of microfluidic wells for repeated experiments; each well included a CNF mat electrode opposing an aluminum electrode. Fluorescent microspheres (1 µm) were trapped at various electric field frequencies between 30 kHz and 1 MHz. Digital images of each well were analyzed to quantify particle trapping. DEP trapping by the CNF mats was greater at all tested frequencies than that of the control of no applied field, and the greatest trapping was observed at a frequency of 600 kHz, where electrothermal flow is more significantly weakened than DEP. Theoretical analysis and measured impedance spectra indicate that this result was due to a combination of the frequency dependence of DEP and capacitive behavior of the well‐based device.
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- Award ID(s):
- 2121008
- PAR ID:
- 10539541
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ELECTROPHORESIS
- ISSN:
- 0173-0835
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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