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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
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
Jemma L Trick, Chen Song, E Jayne Wallace, Mark S P Sansom
It is desirable that nanopores that are components of biosensors are gated, i.e. capable of controllable switching between closed (impermeable) and open (permeable) states. A central hydrophobic barrier within a nanopore may act as a voltage dependent gate via electrowetting, i.e. changes in nanopore surface wettability by application of an electric field. We use 'computational electrophysiology' simulations to demonstrate and characterise electrowetting of a biomimetic nanopore containing a hydrophobic gate...
January 31, 2017: ACS Nano
Junsik Lee, Junoh Kim, Cheoljoong Kim, Dooseub Shin, Gyohyun Koo, Jee Hoon Sim, Yong Hyub Won
In this paper, we used a thin polycarbonate (PC) chamber to improve the performance of an electrowetting lenticular lens array. The polycarbonate chamber changed the radius of curvature (ROC) of the oil acting as a lens, which increased the dioptric power of the liquid lens to 1666.7D. The increase in dioptric power required a reduction in the distance between the optical center of the lens and the display pixels under the chamber, which was accomplished by reducing the thickness of the chamber. The optimal thickness of the chamber was determined to be 0...
December 26, 2016: Optics Express
Deborah Decrop, Elena Pérez Ruiz, Phalguni Tewari Kumar, Lisa Tripodi, Tadej Kokalj, Jeroen Lammertyn
Digital microfluidics has emerged in the last years as a promising liquid handling technology for a variety of applications. Here, we describe in detail how to build up an electrowetting-on-dielectric-based digital microfluidic chip with unique advantages for performing single-molecule detection. We illustrate how superparamagnetic particles can be printed with very high loading efficiency (over 98 %) and single-particle resolution in the microwell array patterned in the Teflon-AF(®) surface of the grounding plate of the chip...
2017: Methods in Molecular Biology
Stéphanie Chevalliot, Géraldine Malet, Herbert Keppner, Bruno Berge
Insulating materials from the parylene family were investigated for use in low-power-consumption electrowetting-based liquid lenses. It was shown that for DC-driven operations, parylene C leads to hysteresis, regardless of the presence of a hydrophobic top coat. This hysteresis was attributed to the non-negligible time needed to reach a stable contact angle, due to charge injection and finite conductivity of the material. It was further demonstrated that by using materials with better insulating properties, such as parylene HT and VT4, satisfactory results can be obtained under DC voltages, reaching a low contact angle hysteresis of below 0...
December 27, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Sarah Holcomb, Michael Brothers, Aaron Diebold, William Thatcher, David Mast, Christopher Tabor, Jason Heikenfeld
Electrowetting and electrocapillarity of liquid metals have a long history, and a recent explosion of renewed interest. Liquid metals have electromagnetic properties and surface tensions (>500 mN/m) that enable new forms of reconfigurable devices. However, the only nontoxic option, gallium alloys, suffer from immediate formation of a semirigid surface oxide. Although acids or electrochemical reduction can remove this oxide, these approaches surround the gallium alloy in a fluid that is also electrically conducting, diminishing electromagnetic effectiveness and precluding electrowetting actuation...
December 6, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Kang Liu, Yishu Zhou, Fang Yuan, Xiaobao Mo, Peihua Yang, Qian Chen, Jia Li, Tianpeng Ding, Jun Zhou
Herein we report a self-powered multimodal temperature and force sensor based on the reverse electrowetting effect and the thermogalvanic effect in a liquid droplet. The deformation of the droplet and the temperature difference across the droplet can induce an alternating pulse voltage and a direct voltage, respectively, which is easy to separate/analyze and can be utilized to sense the external force and temperature simultaneously. In addition, an integral display system that can derive information from external temperature/force concurrently is constructed...
December 19, 2016: Angewandte Chemie
Zhen Zhang, Collin Hitchcock, Robert F Karlicek
The electrowetting-on-dielectric (EWOD) lens is a good candidate for dynamic beam-shaping optics for advanced solid-state lighting systems. A geometric approximation model is described to predict the meniscus shape of a rectangular EWOD lens with arbitrary voltages and small Bond numbers. The model approximates the meniscus geometry as being a part of a compound toroidal surface. The model was compared with free-energy minimization simulations and experiments with the largest standard deviation between the geometric model and the simulation for a wide variety of bias voltages being less than 2%...
November 10, 2016: Applied Optics
Min-Yu Chiang, Yao-Wen Hsu, Hsin-Yi Hsieh, San-Yuan Chen, Shih-Kang Fan
Formation of multifunctional, heterogeneous, and encoded hydrogel building blocks, or microgels, by crosslinking and assembly of microgels are two essential steps in establishing hierarchical, complicated, and three-dimensional (3D) hydrogel architectures that recapitulate natural and biological structures or originate new materials by design. However, for the variety of the hydrogel materials crosslinked differently and for the varied scales of microgels and architectures, the formation and assembly processes are usually performed separately, which increases the manufacturing complexity of designed hydrogel materials...
October 2016: Science Advances
Rassoul Tabassian, Jung-Hwan Oh, Sooyeun Kim, Donggyu Kim, Seunghwa Ryu, Seung-Min Cho, Nikhil Koratkar, Il-Kwon Oh
The wettability of graphene on various substrates has been intensively investigated for practical applications including surgical and medical tools, textiles, water harvesting, self-cleaning, oil spill removal and microfluidic devices. However, most previous studies have been limited to investigating the intrinsic and passive wettability of graphene and graphene hybrid composites. Here, we report the electrowetting of graphene-coated metal meshes for use as electroactive flow control devices, utilizing two antagonistic functions, hydrophobic repellency versus liquid permeability...
October 31, 2016: Nature Communications
Deborah J Lomax, Pallav Kant, Aled T Williams, Hollie V Patten, Yuqin Zou, Anne Juel, Robert A W Dryfe
The control of wetting behaviour underpins a variety of important applications from lubrication to microdroplet manipulation. Electrowetting is a powerful method to achieve external wetting control, by exploiting the potential-dependence of the liquid contact angle with respect to a solid substrate. Addition of a dielectric film to the surface of the substrate, which insulates the electrode from the liquid thereby suppressing electrolysis, has led to technological advances such as variable focal-length liquid lenses, electronic paper and the actuation of droplets in lab-on-a-chip devices...
October 5, 2016: Soft Matter
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
Yogesh B Sawane, Satishchandra B Ogale, Arun G Banpurkar
We demonstrate a consistent electrowetting response on ferroelectric poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) insulator covered with a thin Teflon AF layer. This bilayer exhibits a factor of 3 enhancement in the contact angle modulation compared to that of conventional single-layered Teflon AF dielectric. On the basis of the proposed model the enhancement is attributed to the high value of effective dielectric constant (εeff ≈ 6) of the bilayer. Furthermore, the bilayer dielectric exhibits a hysteresis-free contact angle modulation over many AC voltage cycles...
September 14, 2016: ACS Applied Materials & Interfaces
Lei Li, Di Wang, Chao Liu, Qiong-Hua Wang
We report an ultrathin zoom telescopic objective that can achieve continuous zoom change and has reduced compact volume. The objective consists of an annular folded lens and three electrowetting liquid lenses. The annular folded lens undertakes the main part of the focal power of the lens system. Due to a multiple-fold design, the optical path is folded in a lens with the thickness of ~1.98mm. The electrowetting liquid lenses constitute a zoom part. Based on the proposed objective, an ultrathin zoom telescopic camera is demonstrated...
August 8, 2016: Optics Express
Sin-Hyung Lee, In-Ho Lee, Jiyoon Kim, Chang-Min Keum, Eui-Sang Yu, Sin-Doo Lee
We demonstrated a new architecture of an electrowetting-on-dielectric (EWOD) device to transport a liquid droplet by the spatial modulation of an electric field produced using an embedded undulating electrode. The undulating electrode was constructed on an array of dielectric microstructures with different periods in region by region to generate a gradually varying lateral electric field. The contact angle of a droplet of water on the EWOD surface was found to decrease monotonically from 120 degrees to about 50 degrees with increasing the strength of the electric field...
June 2016: Journal of Nanoscience and Nanotechnology
Guohui Zhang, Marc Walker, Patrick R Unwin
We demonstrate low-voltage electrowetting at the surface of freshly cleaved highly oriented pyrolytic graphite (HOPG). Using cyclic voltammetry (CV), electrowetting of a droplet of a sodium perchlorate solution is observed at moderately positive potentials on high-quality (low step edge coverage) HOPG, leading to significant changes in the contact angle and relative contact diameter that are comparable to the results of the widely studied electrowetting on dielectric (EWOD) system, but over a much lower voltage range...
August 2, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
F Invernizzi, S Dulio, M Patrini, G Guizzetti, P Mustarelli
Energy harvesting from human motion is a research field under rapid development. In this tutorial review we address the main physical and physico-chemical processes which can lead to energy generation, including electromagnetism, piezoelectricity, and electrostatic generation. Emphasis is put on the relationships among material properties and device efficiency. Some new and relatively less known approaches, such as triboelectric nanogeneration (TENG) and reverse electrowetting (REWOD), are reported in more detail...
July 11, 2016: Chemical Society Reviews
Elaheh Shekaramiz, Ganeshkumar Varadarajalu, Philip J Day, H Kumar Wickramasinghe
Single cell transfection techniques are essential to understand the heterogeneity between cells. We have developed an integrated electrowetting nanoinjector (INENI) to transfect single cells. The high transfection efficiency, controlled dosage delivery and ease of INENI fabrication promote the widespread application of the INENI in cell transfection assays.
2016: Scientific Reports
Daniel Kopp, Hans Zappe
We demonstrate a new means to fabricate three-dimensional liquid lenses which may be tuned in focal length and astigmatism. Using actuation by electrowetting-on-dielectrics, astigmatism in arbitrary directions may be tuned independently, with almost no cross talk between orthogonal orientations. The lens is based on electrodes structured on planar polyimide foils and subsequently rolled, enabling high-resolution patterning of complex electrodes along the azimuthal and radial directions of the lens. Based on a design established through fluidic and optical simulations, the astigmatism tuning is experimentally verified by a change of the corresponding Zernike coefficients measured using a Shack-Hartmann wavefront sensor...
June 15, 2016: Optics Letters
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