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Giuseppe Nasti, Sara Coppola, Federico Olivieri, Veronica Vespini, Vito Pagliarulo, Pietro Ferraro
Electrophoresis (EP) and dielectrophoresis (DEP) are two well established methodologies to manipulate nanoparticles (NPs). Recently, a DEP by virtual electrodes platform was demonstrated on ferroelectric substrates where the driving force is due to the strong electric field generated by pyroelectric effect thus opening new scenarios for manipulating the matter. Such innovative approach named pyroelectric-DEP has several advantages over the traditional EP and DEP. However, a detailed study on this novel approach is required for understanding the complex pathways traced by nanoparticles (NP) under the action of the pyroelectric driven forces and thus for explaining the final patterns...
January 10, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Mingrui Sun, Patrick Durkin, Thomas L Toth, Xiaoming He
Microfluidic encapsulation of cells or tissues in biocompatible solid-like hydrogels has wide biomedical applications. However, the microfluidically encapsulated cells/tissues are usually suspended in oil and need to be extracted into aqueous solution for further culture or use. Current extracting techniques are either non-selective for the cell/tissue-laden hydrogel microcapsules or rely on fluorescence labeling of the cells/tissues that may be undesired for their further culture or use. Here we developed a micro-electro-mechanical system to achieve label-free on-chip selective extraction of cell aggregate-laden hydrogel microcapsules from oil into aqueous solution...
January 4, 2018: ACS Sensors
Nuttawut Lewpiriyawong, Guo Lin Xu, Chun Yang
This paper presents the use of DC-biased AC electric field for enhancing cell trapping throughput in an insulator-based dielectrophoretic (iDEP) fluidic device with densely packed silica beads. Cell suspension is carried through the iDEP device by a pressure-driven flow. Under an applied DC-biased AC electric field, DEP trapping force is produced as a result of non-uniform electric field induced by the gap of electrically insulating silica beads packed between two mesh electrodes that allow both fluid and cells to pass through...
December 30, 2017: Electrophoresis
Kaspar Snashall, Marios Constantinou, Maxim Shkunov
Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity...
December 7, 2017: Journal of Visualized Experiments: JoVE
Shigeru Tada, Masako Hayashi, Masanori Eguchi, Akira Tsukamoto
We propose a novel, high-performance dielectrophoretic (DEP) cell-separation flow chamber with a parallel-plate channel geometry. The flow chamber, consisting of a planar electrode on the top and an interdigitated-pair electrode array at the bottom, was developed to facilitate the separation of cells by creating a nonuniform AC electric field throughout the volume of the flow chamber. The operation and performance of the device were evaluated using live and dead human epithermal breast (MCF10A) cells. The separation dynamics of the cell suspension in the flow chamber was also investigated by numerically simulating the trajectories of individual cells...
November 2017: Biomicrofluidics
Colin Chung, Ronald Pethig, Stewart Smith, Martin Waterfall
Dielectrophoresis (DEP) has been widely studied for its potential as a biomarker-free method of sorting and characterizing cells based upon their dielectric properties. Most studies have employed voltage signals from ∼1 kHz to no higher than ∼30 MHz. Within this range a transition from negative to positive DEP can be observed at the cross-over frequency fx01 . The value of fx01 is determined by the conductivity of the suspending medium, as well as the size and shape of the cell and the dielectric properties (capacitance, conductivity) of its plasma membrane...
December 23, 2017: Electrophoresis
Johanna Kirchhoff, Uwe Glaser, Jürgen A Bohnert, Mathias W Pletz, Juergen Popp, Ute Neugebauer
Resistant bacteria are spreading worldwide, which makes fast antibiotic susceptibility testing and determination of the minimal inhibitory concentration (MIC) urgently necessary to select appropriate antibiotic therapy in time and by this improve patient's outcome, and at the same time avoiding inappropriate treatment as well as the unnecessary use of broad spectrum antibiotics which would foster further spread of resistant bacteria. Here, a simple and fast Raman spectroscopy-based procedure is introduced to identify antimicrobial susceptibilities and determine the MIC within only two hours total analysis marking a huge time saving compared to established phenotypic methods nowadays used in diagnostics...
December 20, 2017: Analytical Chemistry
Teng Zhou, Jian Ge, Liuyong Shi, Junqing Fan, Zhenyu Liu, Sang Woo Joo
The translational motion of small particles in an electrokinetic fluid flow through a constriction can be enhanced by an increase of the applied electric potential. Beyond a critical potential, however, the negative dielectrophoresis (DEP) can overpower other forces to prevent particles that are even smaller than the constriction from passing through the constriction. This DEP choking phenomenon was studied previously for rigid particles. Here, the DEP choking phenomenon is revisited for deformable particles, which are ubiquitous in many biomedical applications...
November 29, 2017: Electrophoresis
Avijit Barik, Yao Zhang, Roberto Grassi, Binoy Paulose Nadappuram, Joshua B Edel, Tony Low, Steven J Koester, Sang-Hyun Oh
The many unique properties of graphene, such as the tunable optical, electrical, and plasmonic response make it ideally suited for applications such as biosensing. As with other surface-based biosensors, however, the performance is limited by the diffusive transport of target molecules to the surface. Here we show that atomically sharp edges of monolayer graphene can generate singular electrical field gradients for trapping biomolecules via dielectrophoresis. Graphene-edge dielectrophoresis pushes the physical limit of gradient-force-based trapping by creating atomically sharp tweezers...
November 30, 2017: Nature Communications
Eva-Maria Laux, Frank F Bier, Ralph Hölzel
Employing electric phenomena for the spatial manipulation of bioparticles from whole cells down to dissolved molecules has become a useful tool in biotechnology and analytics. AC electrokinetic effects like dielectrophoresis and AC electroosmosis are increasingly used to concentrate, separate and immobilize DNA and proteins. With the advance of photolithographical micro- and nanofabrication methods, novel or improved bioanalytical applications benefit from concentrating analytes, signal enhancement and locally controlled immobilization by AC electrokinetic effects...
November 23, 2017: Bioelectrochemistry
Yagmur Yildizhan, Nurdan Erdem, Monsur Islam, Rodrigo Martinez-Duarte, Meltem Elitas
Blood has been the most reliable body fluid commonly used for the diagnosis of diseases. Although there have been promising investigations for the development of novel lab-on-a-chip devices to utilize other body fluids such as urine and sweat samples in diagnosis, their stability remains a problem that limits the reliability and accuracy of readouts. Hence, accurate and quantitative separation and characterization of blood cells are still crucial. The first step in achieving high-resolution characteristics for specific cell subpopulations from the whole blood is the isolation of pure cell populations from a mixture of cell suspensions...
November 22, 2017: Sensors
Zhijie Huan, Henry K Chu, Hongbo Liu, Jie Yang, Dong Sun
Patterning of cells into a specific pattern is an important procedure in tissue engineering to facilitate tissue culture and ingrowth. In this paper, a new type of 3D-printed scaffold utilizing dielectrophoresis (DEP) for active cell seeding and patterning was proposed. This scaffold adopted a concentric-ring design that is similar to native bone tissues. The scaffold was fabricated with a commercial three-dimensional (3D) printer. Polylactic Acid (PLA) was selected as the material for the printer and the fabricated scaffold was coated with gold to enhance the conductivity for DEP manipulation...
November 13, 2017: Biomedical Microdevices
Mohammad Towshif Rabbani, Christoph F Schmidt, Alexandra Ros
Single-walled carbon nanotubes (SWNTs) offer unique electrical and optical properties. Common synthesis processes yield SWNTs with large length polydispersity (several tens of nanometers up to centimeters) and heterogeneous electrical and optical properties. Applications often require suitable selection and purification. Dielectrophoresis is one manipulation method for separating SWNTs based on dielectric properties and geometry. Here, we present a study of surfactant and ssDNA wrapped SWNTs suspended in aqueous solutions manipulated by insulator-based dielectrophoresis (iDEP)...
November 13, 2017: Analytical Chemistry
Xin Wang, Ke Chen, Linbo Liu, Nan Xiang, Zhonghua Ni
Abstract Nanowire assembly based on dielectrophoresis (DEP) could be a useful and efficient tool for fabricating nanowire-based devices. Although there have been extensive reports on the DEP nanowire assembly, the new approaches that make DEP more facile and affordable are still desirable. Herein, we present an approach using the reusable electrodes to assemble silver nanowires onto a removable, independent polyethylene terephthalate (PET) film. The PET film is placed on the reusable electrodes, and a sinusoidal AC voltage is applied to the electrodes to induce DEP force for nanowire assembly upon the flexible film...
November 13, 2017: Nanotechnology
Mohammad R Hossan, Diganta Dutta, Nazmul Islam, Prashanta Dutta
Pumping of fluids with precise control is one of the key components in a microfluidic device. The electric field has been used as one of the most popular and efficient nonmechanical pumping mechanism to transport fluids in microchannels from the very early stage of microfluidic technology development. This review presents fundamental physics and theories of the different microscale phenomena that arise due to the application of an electric field in fluids, which can be applied for pumping of fluids in microdevices...
November 11, 2017: Electrophoresis
Sarah Täuber, Lena Kunze, Oleg Grauberger, Armin Grundmann, Martina Viefhues
The efficient purification and analysis of topological DNA variants is mandatory for many state-of-the-art molecular medicine technologies, like gene- and cancer-therapy as well as plasmid vaccination. In this work, we exploit dielectrophoresis (DEP) for a fast and efficient continuous-flow separation and analysis that goes beyond the standard methods of gel electrophoresis and capillary electrophoresis. The aim of this work was to reach for the limits in dielectrophoretic analysis of DNA regarding the size resolution and the topological conformation...
November 9, 2017: Analyst
ChunHui Wu, RiFei Chen, Yu Liu, ZhenMing Yu, YouWei Jiang, Xing Cheng
This paper reports the design and fabrication of a planar chip for high-throughput cell trapping and pairing (more than 2400 single cell-cell pairs in a microwell array) in a 1 × 1.5 cm area by positive dielectrophoresis (p-DEP) within only several minutes. The p-DEP was generated by applying an alternating current signal on a novel two-pair interdigitated array (TPIDA) electrode. The TPIDA electrode not only enabled the planar chip to be incorporated with a most often used PDMS microfluidic channel, but also contributed to a high single cell-cell pairing efficiency up to 74...
November 21, 2017: Lab on a Chip
Kosuke Ino, Mustafa Şen, Hitoshi Shiku, Tomokazu Matsue
Herein, we present an overview of recent research progress in the development of micro/nanoelectrochemical probe and chip devices for the evaluation of three-dimensional (3D) cultured cells. First, we discuss probe devices: a general outline, evaluation of O2 consumption, enzyme-modified electrodes, evaluation of endogenous enzyme activity, and the collection of cell components from cell aggregates are discussed. The next section is focused on integrated chip devices: a general outline, electrode array devices, smart electrode array devices, droplet detection of 3D cultured cells, cell manipulation using dielectrophoresis (DEP), and electrodeposited hydrogels used for fabrication of 3D cultured cells on chip devices are discussed...
November 6, 2017: Analyst
Jaione Tirapu-Azpiroz, Yuksel Temiz, Emmanuel Delamarche
Multiplexing assays using microbeads in microfluidics offers high flexibility and throughput, but requires the ability to sort particles based on their physical properties. In this paper, we present a continuous method for separating microbeads that is compact, modular and adaptive, employing an optimized electrode layout that alternates sorting and concentration of microbeads using dielectrophoresis and a nested design. By simulating the combined effects of the hydrodynamic drag and dielectrophoresis forces on polystyrene beads, the parameters of the electrode layout and voltage configuration are optimized for maximum separation based on particle size with a small number of slanted planar electrodes...
October 30, 2017: Biomedical Microdevices
H Khanbareh, S van der Zwaag, W A Groen
Composites of lead zirconate titanate particles in an epoxy matrix are prepared in the form of 0-3 and quasi 1-3 with different ceramic volume contents from 10% to 50%. Two different processing routes are tested. Firstly a conventional dielectrophoretic structuring is used to induce a chain-like particle configuration, followed by curing the matrix and poling at a high temperature and under a high voltage. Secondly a simultaneous combination of dielectrophoresis and poling is applied at room temperature while the polymer is in the liquid state followed by subsequent curing...
November 2017: Journal of Intelligent Material Systems and Structures
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