Dynamic cell patterning and photopolymerization with electric field modulation for constructing hierarchical tumor microenvironments.

Electrokinetics has established itself as a central pillar in microfluidic research, offering a powerful, non-mechanical means to manipulate fluids and analytes. Mechanisms such as electroosmotic flow (EOF), electrophoresis (EP), and dielectrophoresis (DEP) re-main central to the field, once more layers of complexity emerge heterogeneous interfaces, viscoelastic liquids, or anisotropic droplets are introduced. Five research directions have become prominent. Field-driven manipulation of droplets and emulsions—most strikingly Janus droplets—demonstrates how asymmetric interfacial structures generate unconventional transport modes. Electrokinetic injection techniques follow as a second focus, because sharply defined sample plugs are essential for high-resolution separations and for maintaining analytical accuracy. Control of EOF is then framed as an integrated design challenge that involves tuning surface chemistry, engineering zeta potential, implementing nanoscale patterning, and navigating non-Newtonian flow behavior. Next, electrokinetic instabilities and electrically driven micromixing are examined through the lens of vortex-mediated perturbations that break diffusion limits in low-Reynolds-number flows. Finally, electrokinetic enrichment strategies—ranging from ion concentration polarization focusing to stacking-based preconcentration—demonstrate how trace analytes can be selectively accumulated to achieve detection sensitivity. Ultimately, electrokinetics is converging towards sophisticated integrated platforms and hybrid powering schemes, promising to expand microfluidic capabilities into previously inaccessible domains for analytical chemistry and diagnostics.

There is a growing appreciation that cellular electrical mechanisms play an important role both in cell regulation, and in cell dysregulation in diseases such as cancer. These electrical mechanisms are measured using several different methods, which yield characteristics including the membrane potential, capacitance and conductance, the extracellular (ζ) potential and cytoplasm conductivity. However, since these are measured using different techniques, the combination of all of these (the cancer electrome) has yet to be described. In this paper, we report on the difference between the electromes of cervical cancer cell line HeLa, with clinically-derived primary cervical epithelial cells. These were investigated using dielectrophoresis (DEP) and ζ-potential, with these data then being used to calculate the membrane potential Vm. Results indicate significant differences in membrane conductance and capacitance, membrane potential, ζ-potential and cytoplasm conductivity between the two cell types. Furthermore, treatment with the K+ blocker Tetraethylammonium caused distinct alterations in electrophysiology of the two lineages, pointing towards different roles for K+ in cancer and normal cells. This work presents a novel and cost-effective approach, combining five distinct electrical properties to form a “fingerprint” to characterize and discriminate healthy and malignant cells in a label-free, rapid manner.

Maintaining favorable biological productivities in photosynthetic biomanufacturing systems, especially when the risk of contamination with competing microbes is high, remains a challenge to achieve while maintaining economic feasibility. This study presents a dielectrophoresis (DEP)-based microfluidic approach for isolating a desired strain within a co-culture. The cyanobacterium Synechocystis sp. PCC 6803 (a strain capable of producing the bioplastic precursor polyhydroxybutyrate, or PHB) was enriched from mixed cultures containing the competing cyanobacterium Synechococcus elongatus PCC 7942 (which does not naturally produce PHB). A DEP cascade electrode system was established to increase purification efficiency through sequential enrichment, which leveraged inherent differences in cell morphology and dielectric properties, to achieve the selective separation of these strains under physiological conditions. A substantial increase in the relative abundance of PHB-producing cells was assessed by optical microscopy and flow cytometry characterization, confirming more than five-fold reduction of the Synechococcus fraction in the refined cell mix. The presented electrokinetic platform offers a scalable and effective approach for selectively enhancing desired microbial components within microbial biomanufacturing systems, leading towards improved product yields.

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).

This abstract presents the fabrication of stable CNT-metal junctions for nanodevices based on carbon nanotubes (CNTs). Low dimensional CNT-based devices offer superior electrical properties that make them ideal for high-performance nanosensors and nanoelectronics.1 However, achieving a stable junction containing a few CNTs with non-reactive metals that are commonly used in the semiconductor industry is challenging. This study explores the role of current stress in optimizing CNT-metal junctions, specifically with gold electrodes.In this study, the dielectrophoresis (DEP) method is utilized to align and position a few CNTs with high precision between gold nanoelectrodes. The gold nanoelectrodes are patterned and deposited using the photolithography method. DEP is a phenomenon in which a force is applied to a dielectric particle when it is exposed to a non-uniform electric field. This facilitates the fabrication of CNT-based sensors using high quality and high purity nanotubes, but ensuring a stable contact resistance remains a critical challenge.After the deposition of CNTs using the established DEP technique, current stress is used to decrease the contact resistance and make it stable (see Figure). In this work, the properties of the applied signal are analyzed to determine the current profile required for fast and efficient electromigration. This improves the reliability and efficiency of CNT-based devices which is one of the important steps toward the fabrication of CNT-based devices for practical applications. The benefits of DEP-assisted fabrication combined with controlled electromigration to achieve stable contacts in low dimensional CNT-based devices are highlighted in this study. This contributes to the broader advancement of CNT nanoelectronics by addressing key interface challenges and improving integration with existing semiconductor materials.(1) Ghomian, T.; Burdette, K.; Kizilkaya, O.; Hihath, J.; Farimand, S. A Study on the Temperature Sensitivity of Nanosensors Based on Single-Walled Carbon Nanotubes in Ambient Conditions. IEEE Transactions on Electron Devices 2023, 70 (5), 2489-2494. Figure 1

Dielectrophoresis (DEP) is a powerful tool for manipulating particles using non-uniform electric fields. This study combines numerical simulations and experiments to investigate crossover frequencies (COFs) for micro- and nanoparticles in a 3D microfluidic device with circular traps. MATLAB simulations revealed an inverse relationship between particle size and COF. For microparticles with diameters of 1.03, 2.27, 4.42, and 6.83µm, the COFs were calculated as 769.10, 352.76, 183.96, and 120.51kHz, respectively. For nanoparticles measuring 50, 170, and 500nm, the corresponding COFs were 15.6, 4.62, and 1.57MHz. These results closely matched experimental data. Notably, additional low-frequency pseudo-COFs emerged in experiments for nanoparticles ranging from 2 to 8kHz (50nm), 10 to 50kHz (170nm), and 40 to 100kHz (500nm). These frequencies proportionally increased with nanoparticle size and corresponded to unexpected negative DEP (nDEP)-like behavior under positive DEP (pDEP) conditions. This effect is attributed to low-frequency alternating current electroosmosis (ACEO), which dominates the DEP response of the nanoparticles smaller than 1µm. These findings demonstrate strong agreement between numerical simulations and experimental results while also revealing the limitations of traditional models in predicting nanoparticle behavior under DEP. We expect that these results can also be applied to the manipulation of various bioparticles.

Sorting of desired single cells from a cell population is crucial for many applications in biology and biomedicine that require analysis at the cellular level. Microfluidic dielectrophoresis (DEP)-based single-cell sorting method has been demonstrated as a powerful technology to enable high-throughput and accurate sorting of single cells. However, conventional DEP sorting is mainly performed in the oil phase constrained by solid channels, which restricts the capacity and tunability of the sorting path. Here, we describe an approach to sort single cells on multiple paths in air. Our device allows for tunable ejection of droplets containing single cells in air, which are interrogated and sorted by a microfluidic DEP sorter with a cylindrical electrode, showing a sorting accuracy of >99% for all paths with high survival rates. We demonstrate the utility of our device by isolating multiple subpopulations from a cell sample with three types of cells. Our technology holds the potential to perform sorting on numerous paths, making it applicable for multipurpose sorting from complex heterogeneous cell populations.

Brucellosis is a neglected zoonotic disease that continues to impact global public health and livestock economies, particularly in regions with limited diagnostic infrastructure. Its causative agent, Brucella abortus, is difficult to detect due to its intracellular lifestyle and the nonspecific symptoms it causes in humans. This study demonstrates the experimental application of dielectrophoresis (DEP) in a microfluidic device for the selective manipulation of polystyrene beads and inactivated B. abortus bacteria. By tuning the frequency and medium conductivity, reliable combined negative dielectrophoretic (nDEP) and hydrodynamic flow responses were achieved, leading to the deflection of bacterial cells across the microchannel within a critical vertical window for particle control. Distinct particle trajectories were observed under varying electric field conditions, confirming effective separation without the need for labels or biochemical markers, except for visual validation. This label-free strategy enables rapid sample processing and has the potential to be integrated into portable platforms for on-site diagnostics. The results highlight the feasibility of DEP-based approaches for pathogen separation and support their future implementation in brucellosis surveillance and point-of-care testing.

For over a decade significant progress has been made in the synthesis and characterization of novel nanomaterials. Many of these unique low dimensional materials have promising electrical, optical, quantum, magnetic, and mechanical properties. However, there have been limited improvements in processes and equipment required to integrate these materials into next-generation microelectronics. Dielectrophoresis (DEP) is a leading method for the parallel integration of nanoparticles onto patterned electrodes. However, its application in manufacturing is severely hindered by the rapid decay of the DEP force with distance from the substrate. While microfluidic channels can force nanoparticles into this active range, they do so at the cost of restricting assembly area, decreasing yield, and drastically reducing throughput. We introduce a non-contact, multiphysics assembly technique that incorporates electrophoretic forces to achieve full-wafer nanoparticle integration. This presentation covers the finite element analysis of a novel electrode configuration and provides design and integration recommendations for incorporating nanoparticles into devices. Potential applications include active interposers, optical I/O, and added RF functionality.

Cancers are diseases described by the irregular spread of cells that have developed invasive features, enabling them to invade adjacent tissues. The specific diagnosis and effective management of oncological treatments depend on the timely detection of circulating tumor cells (CTCs) in a patient’s bloodstream. One of the most promising approaches to CTC separation from blood fractions involves the dielectrophoresis (DEP) technique. This research presents a new DEP-based bionic system designed for MDA-MB-231 breast cancer cell isolation from white blood cell (WBC) subtypes with a viable approach to cell viability. This work leverages the principle that every cell type possesses a unique dielectric fingerprint. This dielectrophoresis microfluidic device is designed to act as a scanner, reading these fingerprints to achieve a continuous, label-free separation of cancer cells from blood components with a high efficiency. In the proposed system that consists of three different stages, the first stage allows for separating B-lymphocytes and Monocytes from Granulocytes and MDA-MB-231 cells. The separation of B-lymphocytes from Monocytes occurs in the second step, while the last step concerns the separation of Granulocytes and MDA-MB-231 cells. In the analysis, x-y graphs of the electric potentials, velocity fields, pressure distributions, and cellular DEP forces applied to the cells, as well as the resulting particle paths, are provided. The model predicts that the system operates with a separation efficiency of nearly 92%. This work focuses on an investigation of the impact of electrode potentials, the velocity of cells, the number of electrodes, the width of the channel, and the output angles on enhancing the separation efficiency of particles.

Cell analysis is vital in clinical diagnostics and cell engineering research. Among the various analytical techniques, dielectrophoresis (DEP) is a particularly promising label-free method for distinguishing biological particles, which eliminates the need for fluorescent dyes or magnetic beads. In this study, we present a high-precision single-cell analysis system based on the evaluation of DEP forces in a controlled microfluidic flow environment. The system integrates a microfluidic chamber equipped with an electrode array to exert DEP forces and flow-induced shear forces to facilitate force balance analysis. We quantitatively characterized the DEP response to successfully discriminate between healthy skin cells and cancer cells using the proposed DEP-based cell-sorting platform. The proposed system successfully distinguished between these cell types even when their dielectrophoretic properties were similar, highlighting its potential for sensitive and selective cell classification in biomedical applications.

Dielectrophoresis (DEP) has been used for decades to estimate the passive electrical properties of cells. However, the body of work on cell electrophysiology derived from Clausius-Mossotti analysis of DEP-derived data pales to insignificance against the wider backdrop of cell electrophysiology based on the Goldman-Hodgkin-Katz equation measured by patch clamp, which focuses on membrane potential Vm-a parameter which does not appear in the Clausius-Mossotti model-and values of patch clamp-derived membrane conductance which, shorn of double-layer conductivity, are often orders of magnitude lower than those derived from DEP. Conversely, the body of work on DEP analysis is more substantial than that reporting the electrical properties of the extracellular (ζ) potential. To address this, several studies have recently been published into the interconnections between the electrical properties determined by the Clausius-Mossotti model, Vm, and ζ-potential, which analyzed the effect of varying the suspending medium conductivity over a wide range, from below 50 mSm-1 to above 1.5 Sm-1. The results of these studies identified relationships between the cytoplasm conductivity, Vm, membrane conductance and capacitance, surface conductance, whole-cell resistance, and ζ-potential. Significantly, many of these relationships only become apparent when analyzed as a function of the conductivity of the suspending medium. This paper assembles these interconnections, using several separate studies approaching different parameter connections, to draw together a set of equations which collectively form a "cellular electrome". This demonstrates that analysis of the Clausius-Mossotti factor across multiple conductivities allows determination of not only passive electrical properties, but also the membrane and ζ-potential, and accurately predicts DEP behavior at higher conductivity for the first time.

The scalable fabrication of high‐performance nanowire (NW) photodetectors remains a critical challenge for the integration of nanoscale optoelectronics into practical technologies. This work presents a simple, rapid, and cost‐effective method for the deterministic assembly of single germanium (Ge) NWs between electrode pairs using a modified dielectrophoresis (DEP) setup. By introducing a voltage‐divider configuration with a series resistor, the method enables self‐limiting NW alignment, eliminating the need for nanoscale electrodes or extensive pre‐optimization. Devices fabricated via this approach exhibit high responsivity—exceeding 6 × 105 A W−1 at both 700 and 1550 nm—among the highest reported for single Ge NW photodetectors. This enhanced performance is attributed to asymmetric Schottky junctions and possible optical resonances within the NWs. The method enables the rapid production of single‐NW photodetectors with tunable properties, offering a versatile platform for low‐cost optoelectronic device manufacturing and advancing the feasibility of NW‐based sensing, imaging, and communication technologies.

Colloidal systems offer a versatile platform for probing condensed matter behavior through tunable interactions and direct imaging. While dielectrophoresis (DEP) has previously been used to crystallize colloids, its broader potential for systematically resolving multiple phase transitions within a single system remains underexplored. Here, we build on prior DEP-based approaches by demonstrating a unified single-sample platform that enables continuous, reversible modulation of local volume fraction and interparticle potential via electric field gradients and surfactant-controlled ionic strength. This platform accesses a range of phase states including liquid-BCC, BCC-FCC, and melting, within a sealed sample. Using real-time confocal microscopy and quantitative structural analysis, we track the evolution of order and capture reversible transitions. Our results highlight the ability to controllably switch between distinct crystal symmetries and phase boundaries in situ, offering a powerful tool for studying nonequilibrium transitions and interface dynamics.

Driven by the growing demand for sustainable resource utilization, the recovery of valuable constituents from spent lithium-ion batteries (LIBs) has attracted considerable attention, whereas conventional recycling processes remain energy-intensive, inefficient, and environmentally detrimental. Herein, an efficient and environmentally benign separation strategy integrating dielectrophoresis (DEP) and magnetophoresis (MAP) is proposed for isolating the primary components of “black mass” from spent LIBs, i.e., lithium iron phosphate (LFP) and graphite microparticles. A coupled electric–magnetic–fluid dynamic model is established to predict particle motion behavior, and a custom-designed microparticle separator is developed for continuous LFP–graphite separation. Numerical simulations are performed to analyze microparticle trajectories under mutual effects of DEP and MAP and to evaluate the feasibility of binary separation. Structural optimization revealed that the optimal separator configuration comprised an electrode spacing of 2 mm and a ferromagnetic body length of 5 mm with 3 mm spacing. Additionally, a numerical study also found that an auxiliary flow velocity ratio of 3 resulted in the best particle focusing effect. Furthermore, the effects of key operational parameters, including electric and magnetic field strengths and flow velocity, on particle migration were systematically investigated. The findings revealed that these factors significantly enhanced the lateral migration disparity between LFP and graphite within the separation channel, thereby enabling complete separation of LFP particles with high purity and recovery under optimized conditions. Overall, this study provides a theoretical foundation for the development of high-performance and environmentally sustainable LIBs recovery technologies.

Candidozymaauris is anemergingmultidrug-resistant fungal pathogen that poses significant challengesto healthcare systems worldwide. Its ability to persist on surfacesand resist common disinfectants contributes to rapid nosocomial transmission,making early and acute detection crucial for infection control. Conventionalculture-based identification methods are time-consuming and lack sensitivity,while molecular techniques are expensive and require specialized equipmentand trained personnel. This study explores the use of dielectrophoresis(DEP) for the rapid detection of C. auris by quantifying its dielectric properties using the dielectric single-shellmodel. Furthermore, since glucose plays a fundamental role in yeastmetabolism, including in C. auris,we investigate how glucose metabolism affects its dielectric behavior.Changes in ionic concentrations and enzyme activity induced by glucosemetabolism can alter the electrical properties of C.auris cells, making them more responsive to externalelectric fields. By characterizing these dielectric shifts under glucose-richand glucose-limited conditions, we aim to develop a DEP-based diagnosticplatform for the rapid and label-free detection of C. auris. This approach could provide an effectivealternative to current diagnostic methods, enhancing screening effortsand improving infection control in healthcare settings.

An integrated platform for single-cell biophysical characterizationis presented. Combining dielectrophoresis (DEP) and optical tweezers(OT) within a single experiment, this approach enables the extractionof both electric properties and optical trap stiffness from individual,living cells in suspension without the need for external calibrationbeads, labels, or adherence to surfaces. Unlike traditional population-basedDEP methods, which average over large cell ensembles and obscure cellularheterogeneity, the presented single-cell approach provides preciseDEP spectra and allows direct computation of electric parameters suchas membrane conductivity, permittivity, and cytoplasmic conductivity.The method is compatible with structurally and optically complex particles,such as living cells, overcoming the limitations of calibration proceduresdesigned for spherical, homogeneous particles. It supports repeatedtesting of the same cell, facilitating dynamic studies of cellularresponses to chemical or physical perturbations. OT stiffness measurementsare performed directly on nonadherent cells that otherwise would beexcluded from surface-based assays. The system includes an open-sourcesoftware for data acquisition, automated image-based analysis, andOT and DEP forces computing. It is compatible with various electrodegeometries, making it broadly adaptable to different experimentaldesigns. Overall, this platform offers a robust, label-free methodfor high-resolution, single-cell electric and optic profiling, expandingthe capabilities of DEP and OT in fundamental research, diagnostics,and bioengineering applications.

The pervasive and growing contamination of ecosystems by microplastics (MPs) has emerged as a critical environmental and societal challenge. These synthetic polymer fragments, typically defined as plastic particles smaller than 5 mm, are now recognized not only for their persistence in natural environments but also for their potential to carry adsorbed pollutants and to be ingested by a wide range of organisms, including humans. Of particular concern are MPs in the sub-100 μm range, which are more difficult to isolate and analyze but may exhibit enhanced mobility, reactivity, and bioavailability. The accurate detection, quantification, and chemical characterization of such small MPs are therefore essential for advancing our understanding of their sources, fate, and impacts. However, current analytical approaches—primarily based on filtration, staining, and spectroscopic methods—remain time-consuming and often lack the sensitivity or selectivity required for sub-100 μm particles in complex aqueous matrices. In this study, we present a novel microfluidic strategy for the rapid, in-flow detection and molecular identification of individual MPs in suspension. The method integrates dielectrophoresis (DEP) for the label-free spatial manipulation of particles and Raman microspectroscopy (RM) for their chemical fingerprinting. A custom-fabricated glass microfluidic chip was developed, incorporating electrodes on both the top and bottom surfaces of the main channel to achieve three-dimensional DEP focusing. MPs ranging from 25 to 50 μm in diameter were successfully aligned along the channel's central axis and interrogated in real time using RM. This approach enabled unambiguous, particle-by-particle identification of five widely encountered polymer types: polystyrene (PS), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), both in monodisperse and polydisperse mixtures. Our results demonstrate that DEP/RM coupling offers a powerful and scalable platform for in-flow MPs analysis, combining high spatial resolution and chemical specificity. This proof of concept opens new possibilities for high-throughput and automated detection of MPs in environmental monitoring and water analysis.

Single-cell analysis technologies are pivotal in unraveling complex biological mechanisms, yet existing platforms are often limited to sequencing-based end-point measurements, which fail to capture live cell dynamics. Here, we present a microfluidic- microelectronic device, the Microfluidic dielectrophoretic Arresting System (MiDAS) that employs dielectrophoresis (DEP) for high-throughput single-cell and droplet trapping in a compact array. We tested multiple trap geometries, including a 20 μm-diameter DEP trap for polymer microbeads, fungal and mammalian cells, and a 40 μm-diameter trap for water-in-oil droplets. The platform demonstrates broad sample compatibility, reliably immobilizing cells and beads of varying sizes. By integrating optical imaging and Raman spectroscopy, we enable rapid, non-destructive interrogation of individual cells with temporal resolution. We describe different modes of MiDAS operation to trap and manipulate single-cells or reverse emulsion droplets on demand, with applications in droplet microfluidics. Our MiDAS platform's simple fabrication, robust performance, and broad compatibility with diverse sample types position it as a versatile tool with transformative potential for single-cell analysis, offering researchers an innovative approach to interrogate cellular dynamics with unprecedented precision and throughput.