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https://www.readbyqxmd.com/read/28497970/electrowetting-of-weak-polyelectrolyte-coated-surfaces
#1
Vincent Sénéchal, Hassan Saadaoui, Juan Rodriguez-Hernandez, Carlos Drummond
Polymer coatings are commonly used to modify interfacial properties like wettability, lubrication, or biocompatibility. These properties are determined by the conformation of polymer molecules at the interface. Polyelectrolytes are convenient elementary bricks to build smart materials, given that polyion chain conformation is very sensitive to different environmental variables. Here we discuss the effect of an applied electric field on the properties of surfaces coated with poly(acrylic acid) brushes. By combining atomic force microscopy, quartz crystal microbalance, and contact angle experiments, we show that it is possible to precisely tune polyion chain conformation, surface adhesion, and surface wettability using very low applied voltages if the polymer grafting density and environmental conditions (pH and ionic strength) are properly formulated...
May 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28475183/reversible-ultralow-voltage-liquid-liquid-electrowetting-without-a-dielectric-layer
#2
Nico E A Cousens, Anthony R J Kucernak
Electrowetting-on-dielectric devices typically have operating voltages of 10-20 V. A reduction in the operating voltage could greatly reduce the energy consumption of these devices. Herein, fully reversible one-electrolyte electrowetting of a droplet on a solid metal surface is reported for the first time. A reversible change of 29° for an 800 mV step is achieved. The effects of surface roughness, electrolyte composition, electrolyte concentration and droplet composition are investigated. It was found that there is a dramatic dependence of the reversibility and hysteresis of the system on these parameters, contrary to theoretical predictions...
May 5, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28463225/toward-individually-tunable-compound-eyes-with-transparent-graphene-electrode
#3
Ali Shahini, Hai Jin, Zhixian Zhou, Yang Zhao, Pai-Yen Chen, Jing Hua, Mark Cheng
We present tunable compound eyes made of ionic liquid lenses which are capable of changing both curvatures (R1 and R2 in the lens maker equation) using electrowetting on dielectric (EWOD) and applied pressure individually. The flexible graphene is used as a transparent electrode and has been integrated on a flexible polydimethylsiloxane (PDMS)/parylene hybrid substrate. Graphene electrodes allow large lens aperture diameter between 2.4 mm and 2.74 mm. Spherical aberration analysis has been performed using COMSOL to investigate the optical property of the lens under applied voltage and pressure...
May 2, 2017: Bioinspiration & Biomimetics
https://www.readbyqxmd.com/read/28451662/is-an-electric-field-always-a-promoter-of-wetting-electro-dewetting-of-metals-by-electrolytes-probed-by-in-situ-x-ray-nanotomography
#4
Maryana I Nave, Yu Gu, Yu-Chen Karen Chen-Wiegart, Jun Wang, Konstantin G Kornev
We developed a special electrochemical cell enabling quantitative analysis and in situ X-ray nanotomography of metal/electrolyte interfaces subject to corrosion. Using this cell and applying the nodoid model to describe menisci formed on tungsten wires during anodization, the evolution of the electrolyte surface tension, the concentration of reaction products, and the meniscus contact angle were studied. In contrast to the electrowetting effect, where the applied electric field decreases the contact angle of electrolytes, anodization of the tungsten wires increases the contact angle of the meniscus...
April 28, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28443836/energy-harvesting-from-aperiodic-low-frequency-motion-using-reverse-electrowetting
#5
Tsung-Hsing Hsu, J A Taylor, T N Krupenkin
Mechanical energy harvesting can provide a promising alternative to electrochemical batteries, which are currently widely utilized to power mobile electronics. In this work we present a theoretical analysis of a recently proposed method of mechanical energy harvesting, which combines a reverse electrowetting phenomenon with the fast self-oscillating process of bubble growth and collapse. We investigate the details of the bubble dynamics and analyze the dependence of the energy generation process on the system parameters...
April 26, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28437684/fibrillar-disruption-by-ac-electric-field-induced-oscillation-a-case-study-with-human-serum-albumin
#6
Shubhatam Sen, Monojit Chakraborty, Snigdha Goley, Swagata Dasgupta, Sunando DasGupta
The effect of oscillation induced by a frequency-dependent alternating current (AC) electric field to dissociate preformed amyloid fibrils has been investigated. An electrowetting-on-dielectric type setup has been used to apply the AC field of varying frequencies on preformed fibrils of human serum albumin (HSA). The disintegration potency has been monitored by a combination of spectroscopic and microscopic techniques. The experimental results suggest that the frequency of the applied AC field plays a crucial role in the disruption of preformed HSA fibrils...
April 13, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28436527/electrowetting-on-conductors-anatomy-of-the-phenomenon
#7
Kontad Ounnunkad, Hollie V Patten, Matěj Velický, Anna K Farquhar, Paula A Brooksby, Alison J Downard, Robert A W Dryfe
We have recently reported that reversible electrowetting can be observed on the basal plane of graphite, without the presence of a dielectric layer, in both liquid/air and liquid/liquid configurations. The influence of carbon structure on the wetting phenomenon is investigated in more detail here. Specifically, it is shown that the adsorption of adventitious impurities on the graphite surface markedly suppresses the electrowetting response. Similarly, the use of pyrolysed carbon films, although exhibiting a roughness below the threshold previously identified as the barrier to wetting on basal plane graphite, does not give a noticeable electrowetting response, which leads us to conclude that specific interactions at the water-graphite interface as well as graphite crystallinity are responsible for the reversible response seen in the latter case...
April 24, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28431469/enhanced-response-time-of-electrowetting-lenses-with-shaped-input-voltage-functions
#8
Omkar D Supekar, Mo Zohrabi, Juliet T Gopinath, Victor M Bright
Adaptive optical lenses based on the electrowetting principle are being rapidly implemented in many applications, such as microscopy, remote sensing, displays, and optical communication. To characterize the response of these electrowetting lenses, the dependence upon direct current (DC) driving voltage functions was investigated in a low-viscosity liquid system. Cylindrical lenses with inner diameters of 2.45 and 3.95 mm were used to characterize the dynamic behavior of the liquids under DC voltage electrowetting actuation...
May 2, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28422343/e-maldi-optimized-conditions-during-electrowetting-enhanced-drop-drying-for-maldi-ms
#9
Olena Kudina, Huseyin Burak Eral, Frieder Mugele
We recently showed that electrowetting-enhanced sample preparation for MALDI-MS (eMALDI) can increase the intensity of the MALDI signal by 2-25 times compared to conventional drop drying by concentrating all the dried sample in a single spot rather than leaving behind a heterogeneous coffee stain pattern. Here, we demonstrate that the eMALDI signal enhancement can be further increased to more than 100x by systematically optimizing the electrowetting actuation frequency and amplitude. This enables 30x signal increase for a peptide standard...
April 18, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28422194/field-induced-anomalous-spreading-oscillation-ejection-spinning-and-breaking-of-oil-droplets-on-a-strongly-slipping-water-surface
#10
Sunny Kumar, Bhaskarjyoti Sarma, Ahsok Kumar Dasmahapatra, Amaresh Dalal, Dipankar Narayan Basu, Dipankar Bandyopadhyay
Application of an electric field on an oil droplet floating on the surface of a deionized water bath showed interesting motions such as spreading, oscillation, and ejection. The electric field was generated by connecting a pointed platinum cathode at the top of the oil droplet and a copper anode coated with polymer at the bottom of the water layer. The experimental setup mimicked a conventional electrowetting setup with the exception that the oil was spread on a soft and deformable water isolator. While at relatively lower field intensities we observed spreading of the droplet, at intermediate field intensities the droplet oscillated around the platinum cathode, before ejecting out at a speed as high as ∼5 body lengths per second at even stronger field intensities...
April 19, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28413333/equilibrium-shapes-of-a-heterogeneous-bubble-in-an-electric-field-a-variational-formulation-and-numerical-verifications
#11
Hanxiong Wang, Liping Liu, Dong Liu
The equilibrium shape of a bubble/droplet in an electric field is important for electrowetting over dielectrics (EWOD), electrohydrodynamic (EHD) enhancement for heat transfer and electro-deformation of a single biological cell among others. In this work, we develop a general variational formulation in account of electro-mechanical couplings. In the context of EHD, we identify the free energy functional and the associated energy minimization problem that determines the equilibrium shape of a bubble in an electric field...
March 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28390354/brownian-motion-as-a-new-probe-of-wettability
#12
Jianyong Mo, Akarsh Simha, Mark G Raizen
Understanding wettability is crucial for optimizing oil recovery, semiconductor manufacturing, pharmaceutical industry, and electrowetting. In this letter, we study the effects of wettability on Brownian motion. We consider the cases of a sphere in an unbounded fluid medium, as well as a sphere placed in the vicinity of a plane wall. For the first case, we show the effects of wettability on the statistical properties of the particles' motion, such as velocity autocorrelation, velocity, and thermal force power spectra over a large range of time scales...
April 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28300262/correction-electrowetting-without-external-voltage-using-paint-on-electrodes
#13
Collin B Eaker, Ishan D Joshipura, Logan R Maxwell, Jason Heikenfeld, Michael D Dickey
Correction for 'Electrowetting without external voltage using paint-on electrodes' by Collin B. Eaker et al., Lab Chip, 2017, DOI: .
March 16, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28264153/promotion-of-water-channels-for-enhanced-ion-transport-in-14-nm-diameter-carbon-nanotubes
#14
Jiadong Sheng, Qi Zhu, Xian Zeng, Zhaohui Yang, Xiaohua Zhang
Ion transport plays an important role in solar-to-electricity conversion, drug delivery, and a variety of biological processes. Carbon nanotube (CNT) is a promising material as an ion transporter in the applications of the mimicking of natural ion channels, desalination, and energy harvesting. Here, we demonstrate a unique, enhanced ion transport through a vertically aligned multiwall CNT membrane after the application of an electric potential across CNT membranes. Interestingly, electrowetting arising from the application of an electric potential is critical for the enhancement of overall ion transport rate through CNT membranes...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28248522/interfacial-nanostructure-and-asymmetric-electrowetting-of-ionic-liquids
#15
Zhen Liu, Tong Cui, GuoZhu Li, Frank Endres
In this work, the interfacial nanostructure and electrowetting of ionic liquids having the same 1-ethyl-3-methylimidazolium cation ([EMIm](+)) but different anions such as bis(trifluoromethylsulfonyl)imide (TFSI(-)), trifluoromethylsulfonate (TfO(-)), methylsulfonate (OMs(-)), acetate (OAc(-)), bis(fluorosulfonyl)imide (FSI(-)), dicyanamide (DCA(-)), and tris(pentafluorethyl)trifluorphosphat (FAP(-)) on bare metallic electrodes were investigated. In the investigated voltammetric potential regime, the contact angle versus voltage curve is asymmetric with respect to surface polarity...
March 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28248385/effect-of-oil-on-an-electrowetting-lenticular-lens-and-related-optical-characteristics
#16
Dooseub Shin, Junoh Kim, Cheoljoong Kim, Gyo Hyun Koo, Jee Hoon Sim, Junsik Lee, Yong Hyub Won
While there are many ways to realize autostereoscopic 2D/3D switchable displays, the electrowetting lenticular lens is superior due to the high optical efficiency and short response time. In this paper, we propose a more stable electrowetting lenticular lens by controlling the quantity of oil. With a large amount of oil, the oil layer was broken and the lenticular lens was damaged at relatively low voltage. Therefore, controlling the amount of oil is crucial to obtain the required dioptric power with stability...
March 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28225124/electrowetting-without-external-voltage-using-paint-on-electrodes
#17
Collin B Eaker, Ishan D Joshipura, Logan R Maxwell, Jason Heikenfeld, Michael D Dickey
Electrowetting uses voltage to manipulate small volumes of fluid for applications including lab-on-a-chip and optical devices. To avoid electrochemical reactions, a dielectric often separates the fluid from the electrode, which has the undesired effect of adding processing steps while increasing the voltage necessary for electrowetting. We present a new method to dramatically reduce the complexity of electrode and dielectric fabrication while enabling multiple performance advances. This method relies on a self-oxidizing paint-on liquid-metal electrode that can be fabricated in minutes on rigid, rough, or even elastic substrates, enabling low operation voltages (<1 V), and self-healing upon dielectric breakdown...
March 14, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28217772/dielectrowetting-manipulation-for-digital-microfluidics-creating-transporting-splitting-and-merging-of-droplets
#18
Hongyao Geng, Jian Feng, Lisa Marie Stabryla, Sung Kwon Cho
Generating, splitting, transporting, and merging droplets are fundamental and critical unit operations for digital (droplet-based) microfluidics. State-of-the-art digital microfluidics performs such operations commonly using electrowetting-on-dielectric (EWOD) in the typical configuration of two parallel channel plates. This paper presents such operations using dielectrowetting (derived from liquid dielectrophoresis), not EWOD, with an array of interdigitated electrodes. The major and unique feature is that the present droplet manipulations are effective for conductive (water with/without surfactant) and non-conductive (propylene carbonate) fluids...
March 14, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28194461/a-3d-microblade-structure-for-precise-and-parallel-droplet-splitting-on-digital-microfluidic-chips
#19
Cheng Dong, Yanwei Jia, Jie Gao, Tianlan Chen, Pui-In Mak, Mang-I Vai, Rui P Martins
Existing digital microfluidic (DMF) chips exploit the electrowetting on dielectric (EWOD) force to perform droplet splitting. However, the current splitting methods are not flexible and the volume of the droplets suffers from a large variation. Herein, we propose a DMF chip featuring a 3D microblade structure to enhance the droplet-splitting performance. By exploiting the EWOD force for shaping and manipulating the mother droplet, we obtain an average dividing error of <2% in the volume of the daughter droplets for a number of fluids such as deionized water, DNA solutions and DNA-protein mixtures...
February 14, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28191268/automated-electrotransformation-of-escherichia-coli-on-a-digital-microfluidic-platform-using-bioactivated-magnetic-beads
#20
J A Moore, M Nemat-Gorgani, A C Madison, M A Sandahl, S Punnamaraju, A E Eckhardt, M G Pollack, F Vigneault, G M Church, R B Fair, M A Horowitz, P B Griffin
This paper reports on the use of a digital microfluidic platform to perform multiplex automated genetic engineering (MAGE) cycles on droplets containing Escherichia coli cells. Bioactivated magnetic beads were employed for cell binding, washing, and media exchange in the preparation of electrocompetent cells in the electrowetting-on-dieletric (EWoD) platform. On-cartridge electroporation was used to deliver oligonucleotides into the cells. In addition to the optimization of a magnetic bead-based benchtop protocol for generating and transforming electrocompetent E...
January 2017: Biomicrofluidics
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