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https://www.readbyqxmd.com/read/28930452/electrowetting-on-immersed-conducting-hydrogel
#1
Caroline Duc, Alexis Vlandas, George G Malliaras, Vincent Senez
Conducting polymers demonstrate an interesting ability to change their wettability at ultra-low voltage (<1V). While the conducting hydrogel poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is increasingly used as an interface with biology partly thanks to its mechanical properties, little is known about the electrical control of its wettability. We rely on the captive bubble technique to study this hydrogel property in relevant conditions (fully immerged) We here report that the wettability variations of PEDOT:PSS are driven by an electrowetting phenomenon in contrast to other conducting polymers which are thought to undergo wettability changes due to oxido-reduction reactions...
September 20, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28927830/transport-velocity-of-droplets-on-ratchet-conveyors
#2
REVIEW
Hal R Holmes, Karl F Böhringer
Anisotropic ratchet conveyors (ARC) are a type of digital microfluidic system. Unlike electrowetting based systems, ARCs transport droplets through a passive, micro-patterned surface and applied orthogonal vibrations. The mechanics of droplet transport on ARC devices has yet to be as well characterized and understood as on electrowetting systems. In this work, we investigate how the design of the ARC substrate affects the droplet response to vibrations and perform the first characterization of transport velocity on ARC devices...
September 14, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/28918633/axisymmetric-and-non-axisymmetric-oscillations-of-sessile-compound-droplets-in-open-digital-microfluidic-platform
#3
Shubhi Bansal, Prosenjit Sen
Manipulating droplets of biological fluids in Electrowetting on Dielectric (EWOD) based digital microfluidic platform is a significant challenge due to biofouling and surface contamination. This problem is often addressed by operating in an oil environment. We study an alternate configuration of sessile compound droplets having an aqueous core surrounded by a smaller oil shell. In contrast to conventional EWOD, open digital microfluidic platform enabled by the core-shell configuration will allow electrical, mechanical or optical probes to get unrestricted access to the droplet and thus enabling highly flexible and dynamically reconfigurable lab-on-chip systems...
September 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28809064/electrical-textile-valves-for-paper-microfluidics
#4
Alar Ainla, Mahiar M Hamedi, Firat Güder, George M Whitesides
This paper describes electrically-activated fluidic valves that operate based on electrowetting through textiles. The valves are fabricated from electrically conductive, insulated, hydrophobic textiles, but the concept can be extended to other porous materials. When the valve is closed, the liquid cannot pass through the hydrophobic textile. Upon application of a potential (in the range of 100-1000 V) between the textile and the liquid, the valve opens and the liquid penetrates the textile. These valves actuate in less than 1 s, require low energy (≈27 µJ per actuation), and work with a variety of aqueous solutions, including those with low surface tension and those containing bioanalytes...
August 15, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28772400/a-study-of-dip-coatable-high-capacitance-ion-gel-dielectrics-for-3d-ewod-device-fabrication
#5
Carlos E Clement, Dongyue Jiang, Si Kuan Thio, Sung-Yong Park
We present a dip-coatable, high-capacitance ion gel dielectric for scalable fabrication of three-dimensional (3D) electrowetting-on-dielectric (EWOD) devices such as an n × n liquid prism array. Due to the formation of a nanometer-thick electric double layer (EDL) capacitor, an ion gel dielectric offers two to three orders higher specific capacitance (c ≈ 10 μF/cm²) than that of conventional dielectrics such as SiO₂. However, the previous spin-coating method used for gel layer deposition poses several issues for 3D EWOD device fabrication, particularly when assembling multiple modules...
January 5, 2017: Materials
https://www.readbyqxmd.com/read/28710385/electron-transfer-chain-in-respiratory-complex-i
#6
Daniel R Martin, Dmitry V Matyushov
Complex I is a part of the respiration energy chain converting the redox energy into the cross-membrane proton gradient. The electron-transfer chain of iron-sulfur cofactors within the water-soluble peripheral part of the complex is responsible for the delivery of electrons to the proton pumping subunit. The protein is porous to water penetration and the hydration level of the cofactors changes when the electron is transferred along the chain. High reaction barriers and trapping of the electrons at the iron-sulfur cofactors are prevented by the combination of intense electrostatic noise produced by the protein-water interface with the high density of quantum states in the iron-sulfur clusters caused by spin interactions between paramagnetic iron atoms...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28675400/chemical-physics-of-electroactive-materials-concluding-remarks
#7
Mark W Rutland
It is an honour to be charged with providing the concluding remarks for a Faraday Discussion. As many have remarked before, it is nonetheless a prodigious task, and what follows is necessarily a personal, and probably perverse, view of a watershed event in the Chemical Physics of Electroactive materials. The spirit of the conference was captured in a single sentence during the meeting itself."It is the nexus between rheology, electrochemistry, colloid science and energy storage". The current scientific climate is increasingly dominated by a limited number of global challenges, and there is thus a tendency for research to resemble a football match played by 6 year olds, where everyone on the field chases the (funding) ball instead of playing to their "discipline"...
July 1, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28638145/a-sacrificial-layer-strategy-for-photolithography-on-highly-hydrophobic-surface-and-its-application-for-electrowetting-devices
#8
Han Zhang, Qiuping Yan, Qingyu Xu, Changshi Xiao, Xuelei Liang
Patterning micro-structures on highly hydrophobic surface by photolithography is usually inevitable for fabricating devices based on electrowetting effects. The key challenges for such photolithography processes are how to coat photoresist uniformly and maintain the hydrophobicity of the highly hydrophobic surface, which are usually two contradict aspects. Moreover, the patterned microstructure must adhere to the highly hydrophobic surface excellently, which is critical for device application. However, a simple and robust fabrication process that fulfills all the above requirements was seldom reported...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28628178/jumping-drops-on-hydrophobic-surfaces-controlling-energy-transfer-by-timed-electric-actuation
#9
Zhantao Wang, Dirk van den Ende, Arjen Pit, Rudy Lagraauw, Daniël Wijnperlé, Frieder Mugele
Aqueous sessile drops are launched from a super-hydrophobic surface by electric actuation in an electrowetting configuration with a voltage pulse of variable duration. We show that the jump height, i.e. the amount of energy that is transferred from surface energy to the translational degree of freedom, depends not only on the applied voltage but also in a periodic manner on the duration of the actuation pulse. Specifically, we find that the jump height for a pulse of optimized duration is almost twice as high as the one obtained upon turning off the voltage after equilibration of the drop under electrowetting...
July 19, 2017: Soft Matter
https://www.readbyqxmd.com/read/28580991/spontaneous-electrification-of-fluoropolymer-water-interfaces-probed-by-electrowetting
#10
Arun G Banpurkar, Yogesh Sawane, Sandip M Wadhai, C U Murade, Igor Siretanu, D van den Ende, F Mugele
Fluoropolymers are widely used as coatings for their robustness, water-repellence, and chemical inertness. In contact with water, they are known to assume a negative surface charge, which is commonly attributed to adsorbed hydroxyl ions. Here, we demonstrate that a small fraction of these ions permanently sticks to surfaces of Teflon AF and Cytop, two of the most common fluoropolymer materials, upon prolonged exposure to water. Electrowetting measurements carried out after aging in water are used to quantify the density of 'trapped' charge...
July 1, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28569062/scalable-device-for-automated-microbial-electroporation-in-a-digital-microfluidic-platform
#11
Andrew C Madison, Matthew W Royal, Frederic Vigneault, Liji Chen, Peter B Griffin, Mark Horowitz, George M Church, Richard B Fair
Electrowetting-on-dielectric (EWD) digital microfluidic laboratory-on-a-chip platforms demonstrate excellent performance in automating labor-intensive protocols. When coupled with an on-chip electroporation capability, these systems hold promise for streamlining cumbersome processes such as multiplex automated genome engineering (MAGE). We integrated a single Ti:Au electroporation electrode into an otherwise standard parallel-plate EWD geometry to enable high-efficiency transformation of Escherichia coli with reporter plasmid DNA in a 200 nL droplet...
September 15, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28497970/electrowetting-of-weak-polyelectrolyte-coated-surfaces
#12
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
#13
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...
July 1, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28463225/toward-individually-tunable-compound-eyes-with-transparent-graphene-electrode
#14
Ali Shahini, Hai Jin, Zhixian Zhou, Yang Zhao, Pai-Yen Chen, Jing Hua, Mark Ming-Cheng Cheng
We present tunable compound eyes made of ionic liquid lenses, of which both curvatures (R 1 and R 2 in the lensmaker's equation) can be individually changed using electrowetting on dielectric (EWOD) and applied pressure. Flexible graphene is used as a transparent electrode and is integrated on a flexible polydimethylsiloxane (PDMS)/parylene hybrid substrate. Graphene electrodes allow a large lens aperture diameter of between 2.4 mm and 2.74 mm. Spherical aberration analysis is performed using COMSOL to investigate the optical property of the lens under applied voltage and pressure...
June 8, 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
#15
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...
July 1, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28443836/energy-harvesting-from-aperiodic-low-frequency-motion-using-reverse-electrowetting
#16
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...
July 1, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28437684/fibrillar-disruption-by-ac-electric-field-induced-oscillation-a-case-study-with-human-serum-albumin
#17
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...
July 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28436527/electrowetting-on-conductors-anatomy-of-the-phenomenon
#18
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...
July 1, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28431469/enhanced-response-time-of-electrowetting-lenses-with-shaped-input-voltage-functions
#19
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
#20
O Kudina, H B Eral, F 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 with 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 100 times by systematically optimizing the electrowetting actuation frequency and amplitude. This enables 30 times signal increase for a peptide standard...
June 2017: Journal of Mass Spectrometry: JMS
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