Floating electrode electrowetting on hydrophobic dielectric. Electrowetting from statics to dynamics sciencedirect. Crossscale electric manipulations of cells and droplets. A low voltage, twolevelmetal, and multilayer insulator electrowettingondielectric ewd platform is presented. Layer dimensions and dielectric constants of electrowetting device. Oct 10, 2011 electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. A numerical study of microfluidicdroplet motions in parallelplate electrowetting on dielectric ewod devices by. This work describes the modeling and simulation of planar electrowetting on dielectric ewod. Crane mechanical engineering department, university of south florida abstract electrowetting on dielectric is demonstrated with a thin spincoated fluoropolymer over an aluminum electrode. Latticeboltzmann simulations of electrowetting phenomena. Crossscale electric manipulations of cells and droplets by. Due to the advantages of rapid response and the programmability of droplet movements, electrowetting on dielectric ewod ref. Low voltage electrowettingondielectric for microfluidic. How electrostatic fields change contact angle in electrowetting kwan hyoung kang department of mechanical engineering, pohang university of science and technology, san 31, hyojadong, pohang 790784, republic of korea received august 6, 2002.
Numerical modeling of 3d electrowetting droplet actuation and. Continuous electrowetting in passivating and nonpassivating systems by mehdi khodayari a dissertation submitted in partial fulfillment of the requirements for the degree of doctor of philosophy department of mechanical engineering college of engineering university of south florida comajor professor. Computational modeling and comparisons with experiments. Electrowettingondielectric induced droplet actuation in. The motion of a conductive liquid on a dielectriccoated conductive substrate has been extensively studied in the past as a part of electrowettingondielectric. Introduction research of fluid and droplet shape manipulation by electrowetting is an active field of research and relevant for a wide field of applications, e. A significant contact angle change 12080 is desired to reliably pump the droplet in microchannels for applications such as labonachip. Multilayer insulator for low voltage and breakdown. Besides, this study proves the feasibility of electrowetting by describing the fabrication and testing of different dielectric layers using high voltage switching system. Electrowettingondielectric induced droplet actuation in m n.
The devices did not succeed in separating the beads from the droplets, but the results show many promising options for further investigation. On the other hand, multilayer dielectric has been known as a way to enhance the dielectric reliability by. This paper is concerned with modeling and simulating. Dispensing 300pl droplets from 140nl closed onchip reservoirs was accomplished with as little as 11. Pdf creating, transporting, cutting, and merging liquid droplets by. Electrowettingondielectric ewod allows us to control wettability of droplets on a solid surface using electrical inputs and has been used in a wide range of applications including microfluidics, optical displays, lenses, and others. Electric field effect on the contact angle for nonwetting. Application of a voltage difference between the drop and the base electrode results in a change in the apparent contact angle. Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the cytop surface, without electrical connection to the substrate. These efforts include reducing the liquiddielectric interfacial tension 19, using the materials that have larger. Ewd is believed to be the most feasible and efficient microfluidic actuator for lab on achip applications, as the droplets can be promptly driven to a precise position, which is not achievable. Discretization by electrowettingondielectric ewod was first demonstrated by.
Electrowetting on semiconductors cesar palma 1,a and robert deegan b university of michigan dated. Electrowetting on dielectric ewod methods which demonstrate more stable and reproducible electrical characteristics than direct electrolyteelectrode contact systems 3,4. Floating electrode electrowetting on hydrophobic dielectric with an sio 2 layer mehdi khodayari, benjamin hahne, nathan b. A material system for reliable low voltage anodic electrowetting m. Electrowetting ew and electrowettingondielectric ewod can be used to handle aqueous liquid in microscale without any second liquid medium.
Optimization of the electrowetting chips configuration to. Applications of electrowetting include reprogrammable labonachip systems,4,11 autofocus cell phone lenses,1 and colored oil pixels for laptops and videospeed smart paper. A significant contact angle change 12080 is desired to reliably pump the droplet in microchannels for applications such as labonachip or micrototal analysis systems. Optoelectrowetting oew is a method of liquid droplet manipulation used in microfluidics applications. Fundamentals of ewod, including basic operations on a droplet, 2, 3, 4 dynamics of contact angle variation, 5, 6 and contact angle saturation 7, 8 have been extensively studied. Electrowetting on dielectric ewod is a method that is used to manipulate microliter volumes of fluids in microfluidic devices. We model the fluid dynamics by using heleshaw type equations with a focus on including the relevant boundary phenomena.
In describing the control of droplet position, the term digital microfluidics is more suitable than electrowetting because there are lowsurface tension fluids that can be controlled on such devices but exhibit modest or negligible wetting that is, w 8. The motion of a conductive liquid on a dielectric coated conductive substrate has been extensively studied in the past as a part of electrowetting on dielectric. Next, the magnets were tested in conjunction with singleplate electrowetting. Reverse electrowetting as a new approach to highpower energy. Single and parallel plate electrowetting devices were tested individually and the magnetic microbeads. A commonly used electrowetting setup developed by rinkel et al. The simplest electrowetting situation, used widely in many ewoc and ewod setups, is the spreading of a droplet of conductive liquid on a solid in the presence of an ambient dielectric fluid. Numerical modeling of 3d electrowetting droplet actuation. Reverse electrowetting as a new approach to highpower. However it is followed by high possibility of dielectric failure.
Programmable electrowetting with channels and droplets mdpi. Electrowetting and electrowettingondielectric for microscale liquid handling. Electrowetting on dielectric ewod is arguably the most flexible and powerful tool, used in many loc platforms because there is no need for a closed channel network and external pump to manipulate the droplets or mechanical parts to move or guide the droplets 23456. Low voltage electrowettingondielectric for microfluidic systems.
Dielectric breakdown of several typical polymeric and inorganic insulators. This dependence of applied voltage on dielectric thickness is confirmed through ewod experiments for three different dielectric materials of. The electrowetting response of these bilayer structures was characterized by concurrently measuring contact angle and leakage current during stepped voltage measurements up to failure, showing three electrowetting response regimes. Electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. The electrowetting based microfluidic devices were fabricated according to the layout of the chip shown in fig. The electrowettingbased microfluidic devices were fabricated according to the layout of the chip shown in fig. Fluid dynamics of an electrowettingondielectrics tube.
Modeling of oilwater interfacial dynamics in three. Electrowetting,applications, figure 6 illustrationof thesoft printing process. Cr electrowetting electrodes 150 nm were deposited by sputtering and subsequently lithographically patterned and wet chemically etched. How electrostatic fields change contact angle in electrowetting. Based on eqn 3, f c is varied by the combination of liquids and dielectric layers with different. Numerical modeling of 3d electrowetting droplet actuation and cooling of a hotspot mun mun nahar, govindraj shreyas bindiganavale, jagath. Pdf modeling the fluid dynamics of electrowetting on. Electrowetting on insulatorcoated electrodes eice definition electrowetting is the electrostatically induced decrease of the liquid contact angle at a contact line formed at the intersection of a liquid, solid, and a third fluid that can be a gas or immiscible liquid. The surface used in this report is, more specifically, an electrode covered with dielectrics, hence, called electrowettingondielectric ewod. Electrowetting can be demonstrated by replacing the metal. In a typical electrowettingondielectric ewod setup, a conducting liquid drop is placed on a dielectric layer which is on top of a base electrode.
Using the setup shown in figure 1 with the counter electrode coated with dielectric teflonaf1600 on parylene, walter and fokkink applied a potential 0200v to acheive fast and reversible switching of the contact angle from 110 to 60 of aqueous droplets containing 104 m kno 3. Continuous electrowetting actuation utilizing current. In electrowetting, a fluid is positioned adjacent to an electrode that is coated with a. Electrowettingondielectric ewod is a method that is used to manipulate microliter volumes of fluids in microfluidic devices. Walker and benjamin shapiro, member, ieee abstractthis paper discusses the modeling and simulation of a parallelplate electrowetting on dielectric ewod device that. An ewod device consists of a base substrate, a conducting electrode array, a dielectric layer, and a hydrophobic surface. In this device, a conducting droplet on the hydrophobic surface is manipulated by. Volume 95, issues 23, 1 january 2002, pages 259268.
In these cases, liquid is in direct contact with air. As for the coating of dielectric layer, cooking oil showed the most noticeable results out of all the materials. Generating, splitting, transporting, and merging droplets are fundamental and. Where traditional electrowetting runs into challenges, however, such as in the simultaneous manipulation of multiple droplets. Modeling the fluid dynamics of electrowetting on dielectric ewod article pdf available in journal of microelectromechanical systems 154. Characterization of the motion and mixing of droplets in electrowetting on dielectric devices michael john schertzer doctor of philosophy mechanical and industrial engineering university of toronto 2010 abstract the physical mechanism responsible for droplet manipulation in electrowetting on dielectric ewod devices is not yet fully understood.
In principle, electrowetting can be applied to drops sitting on a bare electrode, or on thin dielectric layer on top of an electrode. In this study, we first present the complete 3d droplet manipulation through the combination of horizontal and vertical droplet actuation between two parallel plates, based on sole alternative current electrowettingondielectric acewod actuation, as shown in fig. This technique builds on the principle of electrowetting, which has proven useful in liquid actuation due to fast switching response times and low power consumption. The emphasis in this experimental study of ewod is on dielectric materials, upon which the performance of ewod devices is heavily dependent. Electrowetting is the modification of the wetting properties of a surface which is typically.
Low voltage electrowettingondielectric platform using. Applications of electrowetting include reprogrammable labonachip systems4,11. Electrowetting on dielectric ewod allows us to control wettability of droplets on a solid surface using electrical inputs and has been used in a wide range of applications including microfluidics, optical displays, lenses, and others. However, most of the recent electrowetting studies and applications are carried out on dielectric, giving rise to the definition of electrowetting on dielectric ewod. Ybarra an abstract of a dissertation submitted in partial ful.
Improvement of droplet speed and stability in electrowetting. All the fluidic movement is confined between two plates, which we call parallelplate channel, rather than through closed channels or on open surfaces. Optimization of the electrowetting chips configuration to transport biofluid drops f. This paper discusses the modeling and simulation of a parallelplate electrowetting on dielectric ewod device that moves fluid droplets through surface tension effects. Volinsky department of mechanical engineering, university of south florida, tampa, florida 33620, usa. Pdf low voltage electrowettingondielectric researchgate. Electrowettingbased microactuation of droplets for digital microfluidics by michael george pollack department of electrical and computer engineering duke university date. The principle of operation is shown figure 1 in which a liquid droplet is sandwiched between two hydrophobiclycoated dielectric glass plates with embedded electrodes. In contrast to previous works, we demonstrate vertical transportation of a droplet without jumping by electrically controlling. Electrowetting has applications in electrowettingbased. This concept is now known as electrowetting on dielectric ewod, which is. Electrowetting and dielectric breakdown voltage versus insulator thickness. Two important electric forces, dielectrophoresis dep and electrowetting ondielectric ewod, are demonstrated by dielectric coated electrodes on a single chip to manipulate objects on. Combining electrowetting and magnetic bead manipulations for use in microfluidic immunoassays amanda barbour.
Dielectrowetting manipulation for digital microfluidics. This work presents the development of electrowetting on dielectric and liquid. October 2, 2002 the electrowetting phenomenon is investigated in the viewpoint of the. This article discusses and experimentally verifies how to lower the operating voltage that drives liquid droplets by the principle of electrowetting on dielectric ewod. A numerical study of microfluidicdroplet motions in parallelplate electrowettingondielectric ewod devices by.
Wirelessly powered electrowettingondielectricewod d. Electrowetting using an insulating layer on top of a bare electrode was later studied by bruno berge in 1993. Electrowetting on this dielectriccoated surface is called electrowettingondielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. Electrowetting ew and electrowetting on dielectric ewod can be used to handle aqueous liquid in microscale without any second liquid medium. Design and fabrication of an electrode for lowactuation. These efforts include reducing the liquid dielectric interfacial tension 19, using the materials that have larger dielectric constant 19,20, using an oil environment. Digital microfluidics electrowetting on dielectric ewod droplet microfluidics dielectric breakdown chemical mechanical polishing cmp these authors contributed equally to this study. Electrowetting on dielectric ewod is a technique for reducing the apparent contact angle of a fluid droplet, which has many promising applications in the fields. Aug 25, 2017 digital microfluidics electrowetting on dielectric ewod droplet microfluidics dielectric breakdown chemical mechanical polishing cmp these authors contributed equally to this study. Efforts have been made to lower the threshold voltage and speedup droplet actuation. Electrowetting on dielectric ewod is the control of contact angles wetting of droplets by applying an electrical voltage between the droplet and the counter electrode coated with a hydrophobic dielectric layer 11. Magnetic bead manipulations in microfluidic devices paper. Electrowetting on dielectric ewod is a promising microfluidic actuation technique. Electrowetting on this dielectric coated surface is called electrowetting on dielectric ewod to distinguish it from the conventional electrowetting on the bare electrode.
Reducing voltage requirements for microfluidics fusayo saeki1, jean baum1, hyejin moon2, jeongyeol yoon3, changjin cj kim2 and robin l. A model of electrowetting, reversed electrowetting, and. Sep 21, 2010 electrowetting on dielectric ewd is an actuator based on controlling charge at the interface of liquids and insulators over buried electrodes 1, 2. In this work materials and fabrication processes for both electrowetting on dielectric. Author links open overlay panel junghoon lee a hyejin moon b jesse fowler b thomas schoellhammer c changjin kim b. A pecvd sio 2 300 nm was again deposited at 350 c for the electrowetting dielectric. Electrodynamic droplet actuation for lab on a chip system. Low voltage electrowettingondielectric platform using multi. Electrowetting on dielectric experiments using graphene. The top plate consisted of an indiumtin oxide itocoated glass. Liquid pixel based on electrowetting on dielectric upcommons. A 4 l droplet of the bead solution was placed on an elevated electrode slide, and a magnet was used to aggregate the beads on one side of the droplet.
Volume and concentration identification by using an. Creating, transporting, cutting, and merging liquid. Electrowetting on dielectric driven droplet resonance and. Small liquid droplet can be created, actuated, merged and split on a ewod platform, so the small.
Characterization of the motion and mixing of droplets in. Sep 18, 2002 this article discusses and experimentally verifies how to lower the operating voltage that drives liquid droplets by the principle of electrowetting on dielectric ewod. Dielectric materials for electrowettingondielectric. Ewod is a phenomenon where a voltage applied to a conducting liquid on a dielectric covered electrode causes. Ewod can be used to improve the throughput and the reliability of biological experiments. Ewod is a phenomenon where a voltage applied to a conducting liquid on a dielectric covered electrode causes the liquid to spread over the dielectric surface 14. Low voltage electrowettingondielectric article pdf available in journal of applied physics 927 october 2002 with 2,764 reads how we measure reads.
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