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ABSTRACT While traditional dielectrophoretic methods for nanoparticle enrichment and filtration are versatile and selective, they struggle to handle higher throughput applications. To address this challenge and enhance the practical application of dielectrophoresis, we propose an innovative design for porous sandwiched nanofiber electrodes. The electrode is fabricated through a simple process involving the electrospinning of nanofibers with a diameter of 216 ± 28 nm and mat thickness of around 70 µm, followed by the deposition of a thin chromium/gold layer (approximately 140 nm thick) on both sides. This process ensures no electrical short circuit occurs between the electrodes, and it maintains a sheet resistance of 7.19 Ω/□. The resulting significant electric field gradients are capable of trapping nanoparticles with diameters of 100 nm and 40 nm. The structure's sub‐micrometer features and large active surface area allow for trapping of nanoparticles at a flow rate of 3.6 mL/h. To evaluate the effects of applied voltage and volumetric flow rate, we conducted experiments with constant voltage while varying the flow rate and constant flow rate while varying the voltage. Our findings indicate that trapping performance improves with higher AC voltage but decreases at higher flow rates. These insights are crucial for optimizing parameters for large‐scale nanoparticle enrichment and filtration. This proof‐of‐concept study for flow through dielectrophoresis of nanoparticles paves the way for a device suitable for large‐scale sample processing and higher throughput/separation efficiency in practical settings. 

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. 

Dielectrophoresis (DEP) is a label-free electrokinetic method for selectively trapping polarizable particles using non-uniform electric fields. While co-planar electrode systems are common, their inherent DEP force distribution limits throughput. This study presents a computationally efficient framework for modeling two-dimensional DEP-based particle trapping in ordered arrays of conductive cylinders. These cylinders are modeled at a range of sizes, from micrometers to nanometers, to represent microfluidic systems consisting of conductive pillars, nanofibers, etc. Analytical solutions for fluid flow and electric potential were derived using eigenfunction expansions and collocation, then used in a particle tracking model that includes hydrodynamic drag, Brownian motion, and multipolar DEP forces. Although focused on conductive arrays, this framework is extensible to other configurations. This work provides a foundation for future work in the design of high-throughput DEP systems. Both dimensionless and dimensional analyses were performed across a wide range of particle sizes (30 nm to 3 μm), voltages (10 mV to 100 V), and array geometries. No specific optimal cylinder size was found; instead, optimal performance arises from a balance between DEP force distribution and flow through the cylinder array gap. Diamond-oriented arrays exhibited enhanced trapping under moderate dielectrophoretic velocity-to-fluid velocity ratios (up to 39% greater), while square arrays performed better under low-field and large-cylinder conditions (up to 40% greater). 

Dielectrophoresis at the nanoscale has gained significant attention in recent years as a low-cost, rapid, efficient, and label-free technique. This method holds great promise for various interdisciplinary applications related to micro- and nanoscience, including biosensors, microfluidics, and nanomachines. The innovation and development of such devices and platforms could promote wider applications in the field of nanotechnology. This review aims to provide an overview of recent developments and applications of nanoparticle dielectrophoresis, where at least one dimension of the geometry or the particles being manipulated is equal to or less than 100 nm. By offering a theoretical foundation to understand the processes and challenges that occur at the nanoscale—such as the need for high field gradients—this article presents a comprehensive overview of the advancements and applications of nanoparticle dielectrophoresis platforms over the past 15 years. This period has been characterized by significant progress, as well as persistent challenges in the manipulation and separation of nanoscale objects. As a foundation for future research, this review will help researchers explore new avenues and potential applications across various fields. 

Trapped nanoparticles on a nanofiber electrode due to AC dielectrophoresis.