The Dielectrophoresis (DEP) phenomenon has been widely used for cell separation in recent years. The experimental measurement of the DEP force is one of the concerns of scientists. This research presents a novel method for more accurately measuring the DEP force. The innovation of this method is considered the friction effect, which has been neglected in previous studies. For this purpose, first, the direction of the microchannel was aligned with the electrodes. As there was no DEP force in this direction, the release force of the cells caused by the fluid flow equaled the friction force between the cells and the substrate. Then, the microchannel was aligned perpendicular to the direction of the electrodes, and the release force was measured. The net DEP force was obtained by the difference between the release forces of these two alignments. In the experimental tests, the DEP force, when applied to the sperm and white blood cell (WBC), was measured. The WBC was used to validate the presented method. The experimental results showed that the forces applied by DEP to WBC and human sperm were 42 pN and 3 pN, respectively. On the other hand, with the conventional method, these figures were as high as 72 pN and 4 pN due to neglecting the friction force. The compression between the simulation results in COMSOL Multiphysics and the experiments determined the new approach to be valid and capable of use in any cell, such as sperm.
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http://dx.doi.org/10.3390/bios13050540 | DOI Listing |
Microsyst Nanoeng
January 2025
Henry Samueli School of Engineering, University of California, Irvine, CA, USA.
In recent decades, electrokinetic handling of microparticles and biological cells found many applications ranging from biomedical diagnostics to microscale assembly. The integration of electrokinetic handling such as dielectrophoresis (DEP) greatly benefits microfluidic point-of-care systems as many modern assays require cell handling. Compared to traditional pump-driven microfluidics, typically used for DEP applications, centrifugal CD microfluidics provides the ability to consolidate various liquid handling tasks in self-contained discs under the control of a single motor.
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December 2024
Department of Applied Physics, National Defense Academy, Hashirimizu 1-10-20, Yokosuka 239-0802, Kanagawa, Japan.
Dielectrophoresis (DEP) cell separation technology is an effective means of separating target cells which are only marginally present in a wide variety of cells. To develop highly efficient cell separation devices, detailed analysis of the nonuniform electric field's intensity distribution within the device is needed, as it affects separation performance. Here we analytically expressed the distributions of the electric field and DEP force in a parallel-plate cell separation DEP device by employing electrostatic analysis through the Fourier series method.
View Article and Find Full Text PDFLab Chip
December 2024
State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instrument, Tsinghua University, Beijing 100084, P. R. China.
The separation of large-size-range particles of complex biological samples is critical but yet well resolved. As a label-free technique, dielectrophoresis (DEP)-based particle separation faces the challenge of how to configure DEP in an integrated microfluidic device to bring particles of various sizes into the effective DEP force field. Herein, we propose a concept that combines the passive flow fraction mechanism with the accumulative DEP deflection effect in a cascaded manner.
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November 2024
Graduate School of Applied Science and Engineering, National Defense Academy, Yokosuka 239-8686, Japan.
Various types of dielectrophoresis (DEP) cell separation devices using AC electric fields have been proposed and developed. However, its capability is still limited by a lack of quantitative characterization of the relationship between frequency and force. In the present study, this limitation was addressed by developing a method capable of fast and accurate quantification of the dielectric properties of biological cells.
View Article and Find Full Text PDFLangmuir
December 2024
Center for Algorithmic and Robotized Synthesis, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea.
Extracellular vesicles (EVs) are small lipid vesicles shed by cells, carrying proteins, nucleic acids, and other molecular fingerprints. EVs have emerged as crucial mediators of cell-to-cell communication and hold great promise as biomarkers for liquid biopsies, enabling disease screening, diagnosis, prognosis, and monitoring. However, conventional EV separation methods are hampered by the presence of lipoproteins (LPs) in plasma samples, which have comparable characteristics and significantly outnumber EVs.
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