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dielectrophoresis

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https://www.readbyqxmd.com/read/28810232/microfluidic-dielectrophoresis-device-for-trapping-counting-and-detecting-shewanella-oneidensis-at-the-cell-level
#1
Xiangyu Chen, Zhiting Liang, Daobo Li, Ying Xiong, Penghui Xiong, Yong Guan, Shuangyue Hou, Yue Hu, Shan Chen, Gang Liu, Yangchao Tian
Shewanella oneidensis, a model organism for electrochemical activity bacteria, has been widely studied at the biofilm level. However, to obtain more information regarding this species, it is essential to develop an approach to trap and detect S. oneidensis at the cell level. In this study, we report a rapid and label-free microfluidic platform for trapping, counting and detecting S. oneidensis cells. A microfluidic chip was integrated with a modified dielectrophoresis (DEP) trapping technique and hole arrays of different hole sizes...
August 8, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28805875/frequency-selective-electrokinetic-enrichment-of-biomolecules-in-physiological-media-based-on-electrical-double-layer-polarization
#2
Ali Rohani, Bankim J Sanghavi, Armita Salahi, Kuo-Tang Liao, Chia-Fu Chou, Nathan S Swami
Proteomic biomarkers of interest to the early diagnosis of diseases and infections are present at trace levels versus interfering species. Hence, their selective enrichment is needed within bio-assays for speeding binding kinetics with receptors and for reducing signal interferences. While DC fields can separate biomolecules based on their electrokinetic mobilities, they are unable to selectively enrich biomarkers versus interfering species, which may possess like-charges. We present the utilization of AC electrokinetics to enable frequency-selective enrichment of nanocolloidal biomolecules, based on the characteristic time constant for polarization of their electrical double-layer, since surface conduction in their ion cloud depends on colloidal size, shape and surface charge...
August 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/28796446/numerical-analysis-of-a-dielectrophoresis-field-flow-fractionation-device-for-the-separation-of-multiple-cell-types
#3
Amir Shamloo, Ali Kamali
In this study, a dielectrophoresis field-flow fractionation device was analyzed using a numerical simulation method and the behaviors of a set of different cells were investigated. By reducing the alternating current frequency of the electrodes from the value used in the original setup configuration and increasing the number of exit channels, total discrimination in cell trajectories and subsequent separation of four cell types were achieved. Cells were differentiated based on their size and dielectric response which are represented in their real part of Clausius-Mossotti factor at different frequencies...
August 10, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28783330/a-simplified-microfluidic-device-for-particle-separation-with-two-consecutive-steps%C3%AF-induced-charge-electroosmotic-prefocusing-and-dielectrophoretic-separation
#4
Xiaoming Chen, Yukun Ren, Weiyu Liu, Xiangsong Feng, Yankai Jia, Ye Tao, Hongyuan Jiang
Continuous dielectrophoretic separation is recognized as a powerful technique for a large number of applications including early-stage cancer diagnosis, water quality analysis, and stem cell-based therapy. Generally, the prefocusing of a particle mixture into a stream is an essential process to ensure all particles are subjected to the same electric field geometry in the separation region. However, accomplishing this focusing process either requires hydrodynamic squeezing, which requires an encumbering peripheral system and a complicated operation to drive and control the fluid motion, or depends on dielectro-phoretic forces, which are highly sensitive to the dielectric characterization of particles...
August 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28782940/electrokinetic-manipulation-of-silver-and-platinum-nanoparticles-and-their-stochastic-electrochemical-detection
#5
Jason Bonezzi, Tulashi Luitel, Aliaksei Boika
Electrokinetic phenomena such as dielectrophoresis and electrothermal fluid flow are used to increase the rate of mass transfer of silver and platinum nanoparticles and improve their stochastic electrochemical detection. These phenomena are induced by applying a high frequency alternating current (ac) waveform between a counter electrode and a working disk microelectrode. By recording chronoamperograms at room temperature and various ac powers, it is shown that the ac heating leads to an increase in the collision frequency of studied nanoparticles with working electrode surface by a factor of ∼10(1)-10(3) as well as the increase in the magnitude of the measured faradaic response...
August 10, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28770923/exploring-the-upper-limit-of-single-walled-carbon-nanotube-purity-by-multiple-cycle-aqueous-two-phase-separation
#6
Li Wei, Benjamin S Flavel, Wenshan Li, Ralph Krupke, Yuan Chen
Ultrahigh purity semiconducting single-walled carbon nanotubes (S-SWCNTs) are required for high-performance transistors. Aqueous two-phase (ATP) separation is an attractive method to obtain such SWCNTs due to its simplicity and scalability. This work targeted two questions; namely what is the upper limit of S-SWCNT purity that can be achieved by multiple cycles of ATP separation from the most commonly used polyethylene glycol and dextran system and how accurately can commonly used methods characterize the improvement in purity? SWCNT purity in nanotube dispersions obtained by multi-cycle ATP separation (2, 4, 6 and 8 cycles) was evaluated by three methods, including UV-vis-NIR absorption spectroscopy analysis, performance of thin-film field effect transistors (FETs) prepared by drop casting and short-channel FET devices prepared by dielectrophoresis deposition...
August 3, 2017: Nanoscale
https://www.readbyqxmd.com/read/28763135/nonlinear-electrokinetic-effects-in-insulator-based-dielectrophoretic-systems
#7
Qianru Wang, Naga Neehar Dingari, Cullen R Buie
Insulator-based dielectrophoresis (iDEP) has emerged as a powerful tool for multiple biomicrofluidic operations, such as cell separation and concentration. The key feature for iDEP systems is the alteration of insulating microchannel geometries to create strong electric field gradients. Under AC electric fields, this strong electric field gradient can affect fluid flow by (at least) two nonlinear electrokinetic phenomena; a) electrothermal flow due to Joule heating and b) induced charge electroosmosis (ICEO) near the microchannel constrictions of small (but finite) permittivity and conductivity...
August 1, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28758660/dielectrophoretic-assembly-of-dimpled-colloids-into-open-packing-structures
#8
Zhuoqiang Jia, Stefano Sacanna, Stephanie S Lee
Reversible solid-state phase transitions between open- and close-packed structures in two-dimensional colloidal crystals comprising 1.8 μm dimpled spherical colloids were observed using negative dielectrophoresis. These asymmetrically-shaped colloids adopted lattices with cmm plane group symmetry and a packing fraction, ϕ, of 0.68 at low electric field strengths. At high electric field strengths, the close-packed p6m symmetry was observed, with ϕ = 0.90. The transition between open and close-packed structures was found to be reversible, depending on the applied electric field strength and frequency...
July 31, 2017: Soft Matter
https://www.readbyqxmd.com/read/28752825/dc-biased-low-frequency-insulating-constriction-dielectrophoresis-for-protein-biomolecules-concentration
#9
Peng Zhang, Yuxin Liu
Sample enrichment or molecules concentration is considered as an essential step for sample processing in miniaturized devices aiming at biosensing and bioanalysis. Among all the means involved to achieve this aim, dielectrophoresis (DEP) is increasingly employed in molecules manipulation and concentration because it is non-destructive and high efficiency. This paper presents a methodology to achieve protein concentration utilizing the combination effects of electrokinetics and low frequency insulator-based dielectrophoresis (iDEP) generated within a microfluidic device, in which a submicron constricted channel was fabricated using DNA molecular combing and replica molding...
July 28, 2017: Biofabrication
https://www.readbyqxmd.com/read/28745290/bacterial-detection-based-on-polymerase-chain-reaction-and-microbead-dielectrophoresis-characteristics
#10
Zhenhao Ding, Hiromichi Kasahara, Michihiko Nakano, Junya Suehiro
In this study, an electrical DNA detection method was applied to bacterial detection. DNA was extracted from bacteria and amplified by polymerase chain reaction. The microbeads were labelled with amplicons, altering their surface conductance and therefore their dielectrophoresis characteristics. Amplicon-labelled microbeads could thus be trapped within a high-strength electric field, where they formed a pearl chain between the electrodes, resulting in an increased conductance between the electrodes. This method reduces the amplicon detection time from 1-2 h to 15 min, compared with the conventional method...
August 2017: IET Nanobiotechnology
https://www.readbyqxmd.com/read/28693315/interlaced-cnt-electrodes-for-bacterial-fouling-reduction-of-microfiltration-membranes
#11
Qiaoying Zhang, Paula Arribas, E Marielle Remillard, M Carmen García-Payo, Mohamed Khayet, Chad D Vecitis
Interlaced carbon nanotube electrodes (ICE) were prepared by vacuum filtering a well-dispersed carbon nanotube-Nafion solution through a laser-cut acrylic stencil onto a commercial polyvinylidene fluoride (PVDF) microfiltration (MF) membrane. Dead-end filtration was carried out using 10(7) and 10(8) CFU mL(-1) Pseudomonas fluorescens to study the effects of the electrochemically active ICE on bacterial density and morphology, as well as to evaluate the bacterial fouling trend and backwash (BW) efficacy, respectively...
July 27, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28683553/exploiting-particle-mutual-interactions-to-enable-challenging-dielectrophoretic-processes
#12
Mario A Saucedo-Espinosa, Blanca H Lapizco-Encinas
Dielectrophoresis (DEP) is the motion of particles under the influence of a nonuniform electric field. In insulator-based dielectrophoresis (iDEP), the required nonuniform electric fields are generated with insulating structures embedded in a microchannel. These structures distort the electric field distribution when an electric potential is applied. This contribution presents an experimental characterization of the electrokinetic (EK) and DEP velocities of a set of target particles, under DC potentials, when additional innocuous particles are used as fillers...
July 25, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28671656/preparation-of-janus-particles-and-alternating-current-electrokinetic-measurements-with-a-rapidly-fabricated-indium-tin-oxide-electrode-array
#13
Yu-Liang Chen, Hong-Ren Jiang
This article provides a simple method to prepare partially or fully coated metallic particles and to perform the rapid fabrication of electrode arrays, which can facilitate electrical experiments in microfluidic devices. Janus particles are asymmetric particles that contain two different surface properties on their two sides. To prepare Janus particles, a monolayer of silica particles is prepared by a drying process. Gold (Au) is deposited on one side of each particle using a sputtering device. The fully coated metallic particles are completed after the second coating process...
June 23, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28658946/heating-enhanced-dielectrophoresis-for-aligned-single-walled-carbon-nanotube-film-of-ultrahigh-density
#14
Qingyuan Gu, Maud Guezo, Hervé Folliot, Thomas Batte, Slimane Loualiche, Julie Stervinou
In this paper, we demonstrate that the alignment density of individualized single-walled carbon nanotubes (SWCNTs) can be greatly improved by heating-enhanced dielectrophoresis (HE-DEP) process. The observations by scanning electron microscope (SEM) suggest ultrahigh alignment density and good alignment quality of SWCNTs. The intuitive alignment density of individualized SWCNTs is much higher than the currently reported best results. The reason of this HE-DEP process is explained by simulation work and ascribed to the heating-enhanced convection process, and the "convection force" induced by the heating effect is assessed in a novel way...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28621527/dielectrophoretic-assembled-single-and-parallel-aligned-ag-nanowire-zno-branched-nanorod-heteronanowire-ultraviolet-photodetectors
#15
Zhi Yang, Minqiang Wang, Qiang Zhao, Hengwei Qiu, Junjie Li, Xiangming Li, Jinyou Shao
The branched hierarchical heteronanowires have been widely studied for optoelectronics application because of their unique electronic and photonic performances. Here, we successfully synthesized Ag nanowire-ZnO-branched nanorod heteronanowires based on an improved hydrothermal method. Then we fabricated single heteronanowire across a Au electrode pair with different gap widths and parallel-aligned heteronanowires on a Au interdigitated electrode with a dielectrophoresis method, indicating the flexibility and operability of the dielectrophoresis assembly method...
July 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28611486/quantitative-measurements-of-dielectrophoresis-in-a-nanoscale-electrode-array-with-an-atomic-force-microscopy
#16
James Froberg, Vidura Jayasooriya, Seungyong You, Dharmakeerthi Nawarathna, Yongki Choi
Nanoelectronic devices integrated with dielectrophoresis (DEP) have been promoted as promising platforms for trapping, separating, and concentrating target biomarkers and cancer cells from a complex medium. Here, we visualized DEP and DEP gradients in conventional nanoelectronic devices by using multi-pass atomic force microcopy techniques. Our measurements directly demonstrated a short range DEP only at sharp step edges of electrodes, frequency dependent DEP polarity, and separation distance dependent DEP strength...
May 15, 2017: Applied Physics Letters
https://www.readbyqxmd.com/read/28609630/high-throughput-selective-capture-of-single-circulating-tumor-cells-by-dielectrophoresis-at-a-wireless-electrode-array
#17
Min Li, Robbyn K Anand
We demonstrate continuous high-throughput selective capture of circulating tumor cells by dielectrophoresis at arrays of wireless electrodes (bipolar electrodes, BPEs). The use of BPEs removes the requirement of ohmic contact to individual array elements, thus enabling otherwise unattainable device formats. Capacitive charging of the electrical double layer at opposing ends of each BPE allows an AC electric field to be transmitted across the entire device. Here, two such designs are described and evaluated...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28608427/breast-cancer-cell-obatoclax-response-characterization-using-passivated-electrode-insulator-based-dielectrophoresis
#18
Sepeedah Soltanian-Zadeh, Kruthika Kikkeri, Ayesha N Shajahan-Haq, Jeannine Strobl, Robert Clarke, Masoud Agah
Inherent electrical properties of cells can be beneficial to characterize different cell lines and their response to experimental drugs. This paper presents a novel method to characterize the response of breast cancer cells to drug stimuli through use of off-chip passivated-electrode insulator-based dielectrophoresis (OπDEP) and the application of AC electric fields. This work is the first to demonstrate the ability of OπDEP to differentiate between two closely related breast cancer cell lines, LCC1 and LCC9 while assessing their drug sensitivity to an experimental anti-cancer agent, Obatoclax...
June 13, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28587929/a-shear-enhanced-cnt-assembly-nanosensor-platform-for-ultra-sensitive-and-selective-protein-detection
#19
Diya Li, Ceming Wang, Gongchen Sun, Satyajyoti Senapati, Hsueh-Chia Chang
Detection and quantification of low-concentration proteins in heterogeneous media are generally plagued by two distinct obstacles: lack of sensitivity due to high dissociation equilibrium constant KD and non-specificity due to an abundance of non-targets with similar KD. Herein, we report a nanoscale protein-sensing platform with a non-equilibrium on-off switch that employs dielectrophoretic and hydrodynamic shear forces to overcome these thermodynamic limitations with irreversible kinetics. The detection sensitivity is achieved with complete association of the antibody-antigen-antibody (Ab-Ag-Ab) complex by precisely and rapidly assembling carbon nanotubes (CNT) across two parallel electrodes via sequential DC electrophoresis and AC dielectrophoresis (DEP), and with single-CNT electron tunneling conductance...
May 31, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28579306/corrigendum-to-a-bead-based-immunofluorescence-assay-on-a-microfluidic-dielectrophoresis-platform-for-rapid-dengue-virus-detection-biosens-bioelectron-95-2017-174-180
#20
Edwar Iswardy, Tien-Chun Tsai, I-Fang Cheng, Tzu-Chuan Ho, Guey Chuen Perng, Hsien-Chang Chang
No abstract text is available yet for this article.
June 1, 2017: Biosensors & Bioelectronics
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