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Microfluidic-Chip Technology for Disease Diagnostic Applications via Dielectrophoresis
Published in Suresh Kaushik, Vijay Soni, Efstathia Skotti, Nanosensors for Futuristic Smart and Intelligent Healthcare Systems, 2022
Soumya K. Srivastava, Anthony T. Giduthuri
Dielectrophoresis, a label-free technique, relies on the particles’ electrophysiological or dielectric properties, suspending medium, and the electrodes’ geometry or insulating structures embedded in the micron-scaled device that introduces motion of the particles under electric field. Smaller particles are harder to manipulate and to maintain viability. Advances in photolithography and rapid prototyping have aided in utilizing biocompatible electrodes like gold and handling a wide range of particles from nano to micron sizes. With the increasing utilization of artificial intelligence (AI) and deep learning algorithms towards precision medicine and health monitoring, researchers have a blooming opportunity to adapt some of these AI tools towards data collection and analysis to improve the sensitivity of dielectrophoretic particle characterization and sorting.
Carbon Nanotube Electronics
Published in Simon Deleonibus, Electronic Device Architectures for the Nano-CMOS Era, 2019
Vincent Derycke, Arianna Filoramo, Jean-Philippe Bourgoin
The second method is based on the dielectrophoresis (DEP) to position nanotubes on a set of predefined microelectrodes.129–134 Dielectrophoresis is based on the appearance of a force on a dielectric object when it is placed in a non-uniform electric field. In the case of an object with a high aspect ratio, such as carbon nanotubes, the dielectrophoretic force aligns the nanotubes along the electric field lines. In this approach, a droplet of solution containing nanotubes is deposited onto a substrate patterned with a set of microelectrodes. The alternating (AC) electric field is applied and traps the nanotubes in the high field region between the microelectrodes. This deposition process depends on various parameters: the electrode geometry, the dielectric characteristic of both the nanotubes and the solvent, the concentration of nanotubes in the solution, the amplitude and frequency of the AC signal and the duration of application of the field. Recently, this method has also been used by Krupke et al.135 to attract predominantly metallic SWNTs to a set of electrodes, exploiting the fact that the magnitude of the DEP force depends on the dielectric and conducting properties of a particle. Moreover, this technique presents another potential advantage, since it can be envisioned, by tuning electrodes geometry and by sequential application of electric fields, to fabricate more complex device structures, such as multiterminal transistors and branching interconnects.133
Solution-Based Fabrication of Carbon Nanotube Thin-Film Logic Gate
Published in Sivashankar Krishnamoorthy, Krzysztof Iniewski, Nanomaterials, 2017
Yan Duan, Jason Juhala, Wei Xue
Dielectrophoresis has emerged as an effective approach for the precise deposition of aligned CNTs. It is a simple process conducted at room temperature under low voltages. A number of parameters such as solution concentration, frequency, deposition period, and AC current amplitude can greatly influence the deposition of CNTs. The process of dielectrophoresis commonly described as the motion of polarized particles in an aqueous environment due to an external, nonuniform electric field. The dielectrophoretic force exerted on a CNT is proportional to the real number part of Clausius-Mossotti factor fcm, which can be simplified as follows: fmεn*−εm*εm*
A review of microfluidic concepts and applications for atmospheric aerosol science
Published in Aerosol Science and Technology, 2018
Andrew R. Metcalf, Shweta Narayan, Cari S. Dutcher
Electric fields applied to microchannels sort particles by the implementation of two distinct physical mechanisms, namely, electrophoresis and dielectrophoresis (Zhu and Xuan 2009). While electrophoretic techniques are effective for particles containing charged species, dielectrophoresis is exhibited by neutral particles subjected to a nonuniform electric field (Rahman et al. 2017). Dielectrophoresis using microelectrodes placed beneath a PDMS channel has been employed to achieve rapid sorting of droplets and particles (Ahn et al. 2006). Forces greater than 10 nN were produced on a water droplet and sorting rates in excess of 1.6 kHz were achieved using this setup. Electrophoresis, while also traditionally applied in applications involving particle or cell sorting (Shields et al. 2015), can be applied to perform measurements of fundamental properties such as electrophoretic mobility and zeta potential (Karam et al. 2017).
Collapse of house-of-cards clay structures and corresponding tailings dewatering induced by alternating electric fields
Published in Drying Technology, 2019
Tinu Abraham, Nhan Lam, Jonathan Xu, Dan Zhang, Harshita Wadhawan, Han Jun Kim, Michael Lee, Thomas Thundat
The mechanisms of colloidal aggregation induced by AC energy in colloidal solutions are well discussed in Morgan and Green.[40] Ions in the electrical double layer (EDL) undergo polarization similar to charges on colloidal particles in presence of a uniform electric field. The charges do not move instantaneously following the application of an electric field, but typically take a few microseconds to reach equilibrium. The role of electrical frequency with the uniform field is to prevent long migrations of charged species and instead enable localized polarizations resulting in formation of induced dipoles.[40] At low frequencies, the movement of free charges in the EDL can keep pace with the changing direction of the field and are dominant form of polarizations that form induced dipoles. At high frequencies, induced dipoles are formed due to dominant polarizations of bound charges in the colloidal particle. Due to formation of induced dipoles and heterogeneity in the particle shape and charge distribution, the electric field strength on one side of the particle could be greater than the other which leads to an imbalance of forces resulting in particle movement called dielectrophoresis. This in turn causes particle aggregation around the initial mean position of the particles. The use of higher electrical frequencies can also result in electro-thermal heating effect from the movement of water molecules.[40] This further increases the kinetic energy which reduces the electrical energy barrier and causes particle aggregation. Having understood the mechanism of aggregation arising from application of AC energy, we will now discuss the results from our observations of aggregation in oil sands tailings.