Materials in mems springer, berlin, heidelberg, 20, p. In this project, a platform for the manipulation of droplets was developed and characterized. Electrowetting on this dielectriccoated surface is called electrowettingondielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. 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. Low thermal stability, evaporation, and a propensity to facilitate corrosion of the metal parts of integrated circuits or electronics are drawbacks of aqueous solutions. 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. This has been termed electrowetting on line electrodes ele. Due to the expensive price of the fabrication process of the existing semiconductor technology, printing technology has become the center of much attention in research as a micro fabrication technology. Emulsification, separation, and manipulation of oilwater. Volume and concentration identification by using an. Electrowetting can be demonstrated by replacing the metal. 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. The pzt thin film is formed by spincoating, pyrolysis and annealing.
Volume 95, issues 23, 1 january 2002, pages 259268. Electrowetting on dielectric ewod discrete microfluidic dmf devices have shown favorable properties for use in microreactor labonachip applications. Among printing technologies, the rreverseoffsetprinting rop method that can achieve high resolution and complicated shape patterns is utilized to fabricate the electrowettingon. Electrowetting based devices flourished upon the discovery that an added dielectric layer between the drop and a conductive electrode would tolerate the application of large voltages, allowing for significant. This phenomenon, known as electrowetting, consists in the spread of a liquid drop placed on an electrode upon application of a voltage. Optical characterisation of a long period grating using. Magnetic bead manipulations in microfluidic devices paper. In cases where the insulating layer is not hydrophobic e. Water or aqueous electrolytes are the dominant components in electrowetting on dielectric ewodbased microfluidic devices. Electrowetting, applications 607 spontaneous electrowetting, on the other hand, arises when a thin frontrunning electrowetting. Electrowetting uses voltage to manipulate small volumes of fluid for applications including lab on achip and optical devices. Electrowetting on dielectric driven droplet resonance and. A low voltage, twolevelmetal, and multilayer insulator electrowettingondielectric ewd platform is presented. Low voltage electrowettingondielectric article pdf available in journal of applied physics 927 october 2002 with 2,764 reads how we measure reads.
Reverse electrowettingondielectric rewod, which is a novel technology for energy harvesting, was demonstrated by depositing al 2 o 3 via atomic layer deposition ald. Automated droplet manipulation through electrowetting on. We demonstrate that, using xps data, independent of the sign of the applied voltage, the droplet. Optical characterisation of a long period grating using liquid droplets on an electrowettingondielectric platform a. Due to the advantages of rapid response and the programmability of droplet movements, electrowetting on dielectric ewod ref. Pdf basics and applications of electrowetting on dielectric ew. Continuous electrowetting at the low concentration electrolyteinsulatorsemiconductor junction. 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. All structured data from the file and property namespaces is available under the creative commons cc0 license. The characterization results show that pzt thin film can serve as the dielectric of ewod with a high dielectric constant and a great. The experimental results indicate that irreversible charge trapping occurred with repeated voltage actuation, resulting in contact angle relaxation and reduction of the ferroelectric film breakdown strength. In electrowetting the balance of forces at the contact point is modified by the application of a voltage between a conducting fluid and the solid surface. Characterization of the motion and mixing of droplets in. Abstract a highly efficient and reliable electrowetting on dielectric ewod digital microfluidics dmf chip is proposed.
Electrowetting electrowetting digital microfluidic circuit cho, sk, et al, creating, transporting, cutting and merging liquid droplets by electrowettingbased actuation for digital microfluidic circuits. October 2, 2002 the electrowetting phenomenon is investigated in the viewpoint of the. Oct 10, 2011 electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. The breakdown voltage depends on dc voltage polarity. Electrowetting ew and electrowetting on dielectric ewod can be used to handle aqueous liquid in microscale without any second liquid medium. Floating electrode electrowetting on hydrophobic dielectric. Electrowetting has applications in electrowettingbased screens 8, vibration energy harvesters 9, lenses 10, and labonachip devices 1114. Rewod with the ald al 2 o 3 thin films exhibited high performances under lowvoltage and. Extra vaporphase silane vps is introduced into the chamber and acts as an aerosol. This paper reports the electrowetting ew properties of silica layers. In this paper, the dielectric and electrowetting properties of pb zr0. This article discusses and experimentally verifies how to lower the operating voltage that drives liquid droplets by the principle of electrowetting on dielectric ewod. Files are available under licenses specified on their description page.
It is important to note that no materials optimization was performed to. Microfluidic processing is performed on unitsized packets of fluid which are transported, stored, mixed, reacted, or analyzed in a discrete manner using a standard set of basic instructions. Electrowettingondielectric actuation of a vertical translation. Dielectric breakdown and failure of ferroelectric films as.
In the fabricated system, the pcb is used as a substrate and is covered with plastic tape. 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. Reverse electrowetting as a new approach to highpower. Electrowetting on this dielectric coated surface is called electrowetting on dielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. In general, the term electrowetting, at least for ewod or. Dec 15, 2015 in this project, a platform for the manipulation of droplets was developed and characterized. Low voltage electrowettingondielectric platform using.
Pdf the shape of liquiddroplet on planar surfaces is mainly governed by resultant surface tension forces at the vapourliquidsolid boundary. Low voltage electrowettingondielectric for microfluidic. Pdf low voltage electrowettingondielectric researchgate. Continuous optoelectrowetting for picoliter droplet. For enabling this scheme, stacked deposition of thin dielectric and hydrophobic layer in that order between microchannel and electrodes is done. This dependence of applied voltage on dielectric thickness is confirmed through ewod experiments for three different dielectric materials of. Piezodriven acoustic streaming in an electrowettingon. Electrowetting on dielectric ewod device with dimple structures. Furthermore, electrowetting optics pose a greater fabrication challenge than optofluidic devices, which often rely on bulky peripherals such as syringe pumps. Electrowetting using an insulating layer on top of a bare electrode was later studied by bruno berge in 1993.
Electrowetting based devices flourished upon the discovery that an added dielectric layer between the drop and a conductive electrode would tolerate the application of. Floating electrode electrowetting on hydrophobic dielectric with an sio 2 layer mehdi khodayari, benjamin hahne, nathan b. Ultralowvoltage electrowetting the journal of physical. Electrowetting is a technique that manipulates liquid using electricity to reduce the contact angle between fluid and a solid surface, thus reducing the surface tension. Ac electrowetting modulation of lowvolatile liquids. Electrowetting 2018 university of twente research information. Ion and liquid dependent dielectric failure in electrowetting systems. Electrowetting on dielectrics ewod is a process of changing the contact angle of a liquid droplet sitting on a dielectriccovered conducting electrode by application of external electric. Specifically, thin layers of al 2 o 3 about 100 nmthick were successfully formed by ald to obtain dense films with high capacit. In contrast to some of the fiber voas described above, our voa used a nonphotorefractive fiber, i.
Modeling and characterization of an electrowetting based. Electrowetting on dielectric ewod has previously been used to modify the. In this paper, we study the electrical properties and breakdown phenomena of pzt ferroelectric thin film in electrowetting systems. Design and fabrication of printed electrowettingon. In this paper, the dielectric and electrowetting properties of pb zr 0. Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the cytop surface, without electrical connection to the substrate. Pdf modeling the fluid dynamics of electrowetting on. We model the fluid dynamics by using heleshaw type equations with a focus on including the relevant boundary phenomena. Electrowetting on dielectric driven droplet resonance and mixing enhancement in parallelplate configuration chiunpeng lee, 1, 2 hsinchien chen, 1, 2 and meifeng lai 1, 2, a 1 department of power mechanical engineering, national tsing hua university, hsinchu, taiwan. Digital microfluidics based on electrowetting on dielectric. Electrowettingbased actuation of liquid droplets for microfluidic applications. Modeling the fluid dynamics of electrowetting on dielectric. 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.
Electrowetting uses voltage to manipulate small volumes of fluid for applications including labonachip and optical devices. Modeling the fluid dynamics of electrowetting on dielectric ewod article pdf available in journal of microelectromechanical systems 154. Nikapitiya 0 mun mun nahar 0 hyejin moon 0 0 mechanical and aerospace engineering department, the university of texas at arlington, arlington, tx 76019, usa this letter reports two novel electrode design. Specifically, thin layers of al 2 o 3 about 100 nmthick were successfully formed by ald to obtain dense films with high capacitances. Charge injection in dielectric films during electrowetting actuation under direct current voltage. By modifying the previous work on mechanical filtration on ewod. A fundamental study on electrowetting by traditional and. Low voltage electrowettingondielectric for microfluidic systems.
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. Using ferroelectric thin film as the dielectric for. In these cases, liquid is in direct contact with air. Reverse electrowetting on dielectric rewod, which is a novel technology for energy harvesting, was demonstrated by depositing al 2 o 3 via atomic layer deposition ald. Uttamchandania a department of electronic and electrical engineering, university of strathclyde, glasgow, g1 1xw, uk. The motion of a conductive liquid on a dielectriccoated conductive substrate has been extensively studied in the past as a part of electrowettingondielectric. Electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration.
Electrowetting without external voltage using painton. The following work looks toward the design and fabrication of ewod devices for the automated droplet manipulation necessary in the ultimate goal of oligonucleotide synthesis. An 8 m parylene c layer is used as the dielectric material. Electrowettingondielectric ewod based droplet actuation in microfluidic chip is designed and fabricated. Low voltage electrowettingondielectric platform using multi. Ewod is used as on chip micropumping scheme for moving fluid digitally in lab on achip devices. Electrowetting on dielectric ewod on a digital microfluidic.
The physical mechanism responsible for droplet manipulation in electrowetting on dielectric ewod devices is not yet fully understood. Highperformance reverse electrowetting energy harvesting. A significant contact angle change 12080 is desired to reliably pump the droplet in microchannels for applications such as labonachip or micrototal analysis systems. One of the roles of the magnetic beads in the immunoassay is to break the. Although the materials tested herein are not compre hensive, this work provides initial guidance on how careful selection and synthesis of liquid and ionic content. Volume and concentration identification by using an electrowetting on dielectric device yiyan li, hongzhong li, and r. Volinsky department of mechanical engineering, university of south florida, tampa fl 33620, usa floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the cytop. 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. Electrowetting,applications, figure 6 illustrationof thesoft printing process.
E electrowetting 601 electrowetting, figure 1 schematic illustration of the various electrode con. For many materials systems used in ew structures, ca saturation is observed at. Electrowetting has applications in electrowettingbased. This surface configuration coupled with the use of a highk dielectric drastically reduces the voltage required to induce electrocoalescence. This investigation will examine the role of capillary forces on droplet manipulation to further the physical understanding of these devices. Spontaneous electrowetting, in contrast, can arise using the parallel line electrode con. Author links open overlay panel junghoon lee a hyejin moon b jesse fowler b thomas schoellhammer c changjin kim b. Electrowetting on dielectric ewod properties of teflon. 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. This paper discusses the modeling and simulation of a parallelplate electrowetting on dielectric ewod device that moves fluid droplets through surface tension effects. Digital microfluidics is an alternative paradigm for labonachip systems based upon micromanipulation of discrete droplets. The surface roughness measurements revealed an increase in roughness with increasing electrospraying time. Thin nanocomposite dielectrics were spin casted from batio3 nanopowder dispersed in a. In many applications the solid surface consists of a thin dielectric deposited onto a conducting layer.
Continuous optoelectrowetting for picoliter droplet manipulation p. Accurate, consistent, and fast droplet splitting and. 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. Micro and nano syst lett accurate, consistent, and fast droplet splitting and dispensing in electrowetting on dielectric digital microfluidics n.
Ewod is used as onchip micropumping scheme for moving fluid digitally in labonachip devices. Ewod is a phenomenon where a voltage applied to a conducting liquid on a dielectric covered electrode causes. Electrowetting on dielectric experiments using graphene. Electrowetting and electrowettingondielectric for microscale liquid handling.
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