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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.