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Seim Timung, Joydip Chaudhuri, Manash Pratim Borthakur, Tapas Kumar Mandal, Gautam Biswas, Dipankar Bandyopadhyay
We report a facile and non-invasive way to disintegrate a microdroplet into a string of further miniaturized ones under the influence of an external electrohydrodynamic field inside a microchannel. The deformation and breakup of the droplet was engendered by the Maxwell's stress originating from the accumulation of induced and free charges at the oil-water interface. While at smaller field intensities, e.g. less than 1 MV/m, the droplet deformed into a plug, at relatively higher field intensities, e.g. ∼1...
October 17, 2016: Electrophoresis
Shirui Luo, Jarrod Schiffbauer, Tengfei Luo
Electric field assisted coalescence is one of the most efficient methods for water-in-oil emulsion separation. In this paper, we experimentally study water droplet evolution in an oil phase under different electric field configurations. We determine that non-uniform fields can enhance the performance of electrocoalescence compared to uniform fields. The analysis indicates that the enhanced coalescence is due to the combined effects of dipole-dipole interaction between droplets and dielectrophoresis between individual droplets and the applied non-uniform field...
October 17, 2016: Physical Chemistry Chemical Physics: PCCP
Javier L Prieto, Hao-Wei Su, Han Wei Hou, Miguel Pinilla Vera, Bruce D Levy, Rebecca M Baron, Jongyoon Han, Joel Voldman
Sepsis is a potentially lethal condition that may be ameliorated through early monitoring of circulating activated leukocytes for faster stratification of severity of illness and improved administration of targeted treatment. Characterization of the intrinsic electrical properties of leukocytes is label-free and can provide a quick way to quantify the number of activated cells as sepsis progresses. Iso-dielectric separation (IDS) uses dielectrophoresis (DEP) to characterize the electrical signatures of cells...
October 7, 2016: Lab on a Chip
Andrew M J Edwards, Rodrigo Ledesma-Aguilar, Michael I Newton, Carl V Brown, Glen McHale
Wetting and dewetting are both fundamental modes of motion of liquids on solid surfaces. They are critically important for processes in biology, chemistry, and engineering, such as drying, coating, and lubrication. However, recent progress in wetting, which has led to new fields such as superhydrophobicity and liquid marbles, has not been matched by dewetting. A significant problem has been the inability to study the model system of a uniform film dewetting from a nonwetting surface to a single macroscopic droplet-a barrier that does not exist for the reverse wetting process of a droplet spreading into a film...
September 2016: Science Advances
Di Li, Xinyu Lu, Yongxin Song, Junsheng Wang, Dongqing Li, Xiangchun Xuan
Particle separation has found practical applications in many areas from industry to academia. Current electrokinetic particle separation techniques primarily rely on dielectrophoresis, where the electric field gradients are generated by either active microelectrodes or inert micro-insulators. We develop herein a new type of electrokinetic method to continuously separate particles in a bifurcating microchannel. This sheath-free separation makes use of the inherent wall-induced electrical lift to focus particles towards the centerline of the main-branch and then deflect them to size-dependent flow paths in each side-branch...
September 2016: Biomicrofluidics
Kosti Tuomas Olavi Tapio, Jenni Leppiniemi, Boxuan Shen, Vesa P Hytönen, Wolfgang Fritzsche, J Jussi Toppari
DNA based structures offer an adaptable and robust way to develop customized nanostructures for various purposes in bionanotechnology. One main aim in this field is to develop a DNA nano-breadboard for a controllable attachment of nanoparticles or biomolecules to form specific nanoelectronic devices. Here we conjugate three gold nanoparticles on a defined size TX-tile assembly into a linear pattern to form nanometer scale isolated islands that could be utilized in a room temperature single electron transistor...
October 4, 2016: Nano Letters
Zuzana Brabcova, Glen McHale, Gary George Wells, Carl V Brown, Michael Ian Newton, Andrew M J Edwards
The wetting of solid surfaces can be modified by altering the surface free energy balance between the solid, liquid, and vapour phases. Liquid dielectrophoresis (L-DEP) can produce wetting on normally non-wetting surfaces, without modification of the surface topography or chemistry. L-DEP is a bulk force acting on the dipoles of a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. However, if this force is induced by a non-uniform electric field across a solid-liquid interface, it can be used to enhance and control the wetting of a dielectric liquid...
October 3, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Victor Hugo Perez-Gonzalez, Roberto Carlos Gallo-Villanueva, Sergio Camacho-Leon, Jose Isabel Gomez-Quiñones, Jose Manuel Rodriguez-Delgado, Sergio Omar Martinez-Chapa
Circulating tumour cells (CTCs) are active participants in the metastasis process and account for ∼90% of all cancer deaths. As CTCs are admixed with a very large amount of erythrocytes, leukocytes, and platelets in blood, CTCs are very rare, making their isolation, capture, and detection a major technological challenge. Microfluidic technologies have opened-up new opportunities for the screening of blood samples and the detection of CTCs or other important cancer biomarker-proteins. In this study, the authors have reviewed the most recent developments in microfluidic devices for cells/biomarkers manipulation and detection, focusing their attention on immunomagnetic-affinity-based devices, dielectrophoresis-based devices, surface-plasmon-resonance microfluidic sensors, and quantum-dots-based sensors...
October 2016: IET Nanobiotechnology
Cristina Páez-Avilés, Esteve Juanola-Feliu, Jaime Punter-Villagrasa, Beatriz Del Moral Zamora, Antoni Homs-Corbera, Jordi Colomer-Farrarons, Pere Lluís Miribel-Català, Josep Samitier
Bacteria concentration and detection is time-consuming in regular microbiology procedures aimed to facilitate the detection and analysis of these cells at very low concentrations. Traditional methods are effective but often require several days to complete. This scenario results in low bioanalytical and diagnostic methodologies with associated increased costs and complexity. In recent years, the exploitation of the intrinsic electrical properties of cells has emerged as an appealing alternative approach for concentrating and detecting bacteria...
2016: Sensors
Shengbo Sang, Qiliang Feng, Aoqun Jian, Huiming Li, Jianlong Ji, Qianqian Duan, Wendong Zhang, Tao Wang
Hemolytic anemia intensity has been suggested as a vital factor for the growth of certain clinical complications of sickle cell disease. However, there is no effective and rapid diagnostic method. As a powerful platform for bio-particles testing, biosensors integrated with microfluidics offer great potential for a new generation of portable point of care systems. In this paper, we describe a novel portable microsystem consisting of a multifunctional dielectrophoresis manipulations (MDM) device and a surface stress biosensor to separate and detect red blood cells (RBCs) for diagnosis of hemolytic anemia...
2016: Scientific Reports
Alicia Boymelgreen, Gilad Yossifon, Touvia Miloh
Previously, metallodielectric Janus particles have been shown to travel with their dielectric hemisphere forward under low frequency applied electric fields as a result of asymmetric induced-charge electroosmotic flow. Here, it is demonstrated that at high frequencies, well beyond the charge relaxation time of the electric double layer induced around the particle, rather than the velocity decaying to zero, the Janus particles reverse direction, traveling with their metallic hemisphere forward. It is proposed that such motion is the result of a surface force, arising from localized nonuniform electric field gradients, induced by the dual symmetry-breaking of an asymmetric particle adjacent to a wall, which act on the induced dipole of the particle to drive net motion even in a uniform AC field...
September 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Tzu-Keng Chiu, Wen-Pin Chou, Song-Bin Huang, Hung-Ming Wang, Yung-Chang Lin, Chia-Hsun Hsieh, Min-Hsien Wu
Circulating tumour cells (CTCs) in a blood circulation system are associated with cancer metastasis. The analysis of the drug-resistance gene expression of cancer patients' CTCs holds promise for selecting a more effective therapeutic regimen for an individual patient. However, the current CTC isolation schemes might not be able to harvest CTCs with sufficiently high purity for such applications. To address this issue, this study proposed to integrate the techniques of optically induced dielectrophoretic (ODEP) force-based cell manipulation and fluorescent microscopic imaging in a microfluidic system to further purify CTCs after the conventional CTC isolation methods...
2016: Scientific Reports
Avijit Barik, Xiaoshu Chen, Sang-Hyun Oh
We demonstrate nanogap electrodes for rapid, parallel, and ultralow-power trapping of nanoparticles. Our device pushes the limit of dielectrophoresis by shrinking the separation between gold electrodes to sub-10 nm, thereby creating strong trapping forces at biases as low as the 100 mV ranges. Using high-throughput atomic layer lithography, we manufacture sub-10 nm gaps between 0.8 mm long gold electrodes and pattern them into individually addressable parallel electronic traps. Unlike pointlike junctions made by electron-beam lithography or larger micron-gap electrodes that are used for conventional dielectrophoresis, our sub-10 nm gold nanogap electrodes provide strong trapping forces over a mm-scale trapping zone...
October 12, 2016: Nano Letters
Shuailong Zhang, Joan Juvert, Jonathan M Cooper, Steven L Neale
Optoelectronic tweezers (OET) or light-patterned dielectrophoresis (DEP) has been developed as a micromanipulation technology for controlling micro- and nano-particles with applications such as cell sorting and studying cell communications. Additionally, the capability of moving small objects accurately and assembling them into arbitrary 2D patterns also makes OET an attractive technology for microfabrication applications. In this work, we demonstrated the use of OET to manipulate conductive silver-coated Poly(methyl methacrylate) (PMMA) microspheres (50 μm diameter) into tailored patterns...
2016: Scientific Reports
Jung Hwal Shin, Kanghyun Kim, Taechang An, WooSeok Choi, Geunbae Lim
Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles...
December 2016: Nanoscale Research Letters
Clarisse Vaillier, Thibault Honegger, Frédérique Kermarrec, Xavier Gidrol, David Peyrade
Dielectrophoresis is widely used for cell characterization, and the exerted force on cells depends on the difference of polarizability between the latter and the surrounding medium. This physical phenomenon is translated by the real part of the Clausius-Mossotti factor. It is mostly modeled from the imaginary part, measured by electrorotation. The method described here measures experimentally the real part of the Clausius-Mossotti factor. It relies on the cell velocity when submitted to pure dielectrophoresis, and it was conducted on several human cell lines, at different times...
September 20, 2016: Analytical Chemistry
Anja Henning-Knechtel, Matthew Wiens, Mathias Lakatos, Andreas Heerwig, Frieder Ostermaier, Nora Haufe, Michael Mertig
DNA nanostructures are promising construction materials to bridge the gap between self-assembly of functional molecules and conventional top-down fabrication methods in nanotechnology. Their positioning onto specific locations of a microstructured substrate is an important task towards this aim. Here we study manipulation and positioning of pristine and of gold nanoparticle-conjugated tubular DNA origami structures using ac dielectrophoresis. The dielectrophoretic behavior was investigated employing fluorescence microscopy...
2016: Beilstein Journal of Nanotechnology
Joshua Raveendran, Jeffery A Wood, Aristides Docoslis
The formation of ordered and regularly shaped structures of colloidal particles with the aid of spatially nonuniform electric fields is a modern research area of great interest. This work illustrates how alternating current (AC) electrokinetic effects (dielectrophoresis, electroosmosis) can serve as contact-free templates, inside which colloidal microspheres can assemble into a variety of shapes and sizes. We show how three-dimensional colloidal structures of square, circular, and diamond shape of many tens of micrometers in size can be reproducibly formed with a single set of quadrupolar microelectrodes...
September 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Hung-Wei Wu, Yao-Sheng Huang, Hsin-Ying Lee, Wu-Han Tsai, Kuan-Yu Chen, Li-Yi Jian
This article describes a high-efficiency light-induced dielectrophoresis biochip containing a thin film prepared through inductively coupled plasma chemical vapor deposition (ICPCVD). The biochip comprises two ITO glass substrates and a photoconductive amorphous silicon thin film. The biochip can effectively sort particular particles (or cells) by projecting visible light onto the surface of the silicon thin film. The sorting efficiency of biochips is highly associated with the quality of the deposited amorphous silicon thin films; therefore, the choice of deposition technique is extremely critical...
October 2016: Biomedical Microdevices
Shoji Tanaka, Makusu Tsutsui, Hu Theodore, He Yuhui, Akihide Arima, Tetsuro Tsuji, Kentaro Doi, Satoyuki Kawano, Masateru Taniguchi, Tomoji Kawai
Understanding and controlling electrophoretic motions of nanoscopic objects in fluidic channels are a central challenge in developing nanopore technology for molecular analyses. Although progress has been made in slowing the translocation velocity to meet the requirement for electrical detections of analytes via picoampere current measurements, there exists no method useful for regulating particle flows in the transverse directions. Here, we report the use of dielectrophoresis to manipulate the single-particle passage through a solid-state pore...
2016: Scientific Reports
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