Electrowetting uses voltage to manipulate small volumes of fluid for applications including lab on achip and optical devices. Modeling the fluid dynamics of electrowetting on dielectric ewod article pdf available in journal of microelectromechanical systems 154. Low thermal stability, evaporation, and a propensity to facilitate corrosion of the metal parts of integrated circuits or electronics are drawbacks of aqueous solutions. An 8 m parylene c layer is used as the dielectric material. Furthermore, electrowetting optics pose a greater fabrication challenge than optofluidic devices, which often rely on bulky peripherals such as syringe pumps. Electrowetting on dielectric ewod has previously been used to modify the. Design and fabrication of printed electrowettingon. Dc electrowetting of nonaqueous liquid revisited by xps. In this paper, we study the electrical properties and breakdown phenomena of pzt ferroelectric thin film in electrowetting systems. This dependence of applied voltage on dielectric thickness is confirmed through ewod experiments for three different dielectric materials of. 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. 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. Ion and liquid dependent dielectric failure in electrowetting systems. In cases where the insulating layer is not hydrophobic e.
Electrowettingbased actuation of liquid droplets for microfluidic applications. Floating electrode electrowetting on hydrophobic dielectric with an sio 2 layer mehdi khodayari, benjamin hahne, nathan b. 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. Uttamchandania a department of electronic and electrical engineering, university of strathclyde, glasgow, g1 1xw, uk. Electrowetting based devices flourished upon the discovery that an added dielectric layer between the drop and a conductive electrode would tolerate the application of. 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.
In this paper, the dielectric and electrowetting properties of pb zr0. 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. Electrowetting on dielectric driven droplet resonance and. Charge injection in dielectric films during electrowetting actuation under direct current voltage. 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. October 2, 2002 the electrowetting phenomenon is investigated in the viewpoint of the.
This surface configuration coupled with the use of a highk dielectric drastically reduces the voltage required to induce electrocoalescence. Automated droplet manipulation through electrowetting on. This article discusses and experimentally verifies how to lower the operating voltage that drives liquid droplets by the principle of electrowetting on dielectric ewod. 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. Modeling and characterization of an electrowetting based. Electrowetting on dielectric ewod discrete microfluidic dmf devices have shown favorable properties for use in microreactor labonachip applications. Spontaneous electrowetting, in contrast, can arise using the parallel line electrode con. A significant contact angle change 12080 is desired to reliably pump the droplet in microchannels for applications such as labonachip or micrototal analysis systems. For enabling this scheme, stacked deposition of thin dielectric and hydrophobic layer in that order between microchannel and electrodes is done. Electrowetting without external voltage using painton. Electrowetting using an insulating layer on top of a bare electrode was later studied by bruno berge in 1993.
Micro and nano syst lett accurate, consistent, and fast droplet splitting and dispensing in electrowetting on dielectric digital microfluidics n. 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. A highly efficient and reliable electrowetting on dielectric. In this paper, the dielectric and electrowetting properties of pb zr 0.
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. In this project, a platform for the manipulation of droplets was developed and characterized. Electrowetting on dielectric experiments using graphene. Ultralowvoltage electrowetting the journal of physical. A low voltage, twolevelmetal, and multilayer insulator electrowettingondielectric ewd platform is presented. Low voltage electrowettingondielectric for microfluidic. Ewod is used as on chip micropumping scheme for moving fluid digitally in lab on achip devices. Accurate, consistent, and fast droplet splitting and. Reverse electrowetting as a new approach to highpower. Low voltage electrowettingondielectric article pdf available in journal of applied physics 927 october 2002 with 2,764 reads how we measure reads. 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. One of the roles of the magnetic beads in the immunoassay is to break the. 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. Files are available under licenses specified on their description page.
Electrowetting and electrowettingondielectric for microscale liquid handling. Using ferroelectric thin film as the dielectric for. Strong charge trapping and bistable electrowetting on. Ac electrowetting modulation of lowvolatile liquids. The pzt thin film is formed by spincoating, pyrolysis and annealing. It is important to note that no materials optimization was performed to. 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.
Digital microfluidics based on electrowetting on dielectric ewod devices has. Reverse electrowettingondielectric rewod, which is a novel technology for energy harvesting, was demonstrated by depositing al 2 o 3 via atomic layer deposition ald. Electrowetting on dielectric ewod based droplet actuation in microfluidic chip is designed and fabricated. In general, the term electrowetting, at least for ewod or. Specifically, thin layers of al 2 o 3 about 100 nmthick were successfully formed by ald to obtain dense films with high capacit. Materials in mems springer, berlin, heidelberg, 20, p. The motion of a conductive liquid on a dielectriccoated conductive substrate has been extensively studied in the past as a part of electrowettingondielectric. For many materials systems used in ew structures, ca saturation is observed at. Low voltage electrowettingondielectric platform using multi. Electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. Electrowetting,applications, figure 6 illustrationof thesoft printing process. Electrowetting can be demonstrated by replacing the metal. Optical characterisation of a long period grating using.
The method of manipulating oil and water presented in this thesis is the electrowetting of a water drop on bare silicon in an oil environment containing zwitterions. 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. This investigation will examine the role of capillary forces on droplet manipulation to further the physical understanding of these devices. Electrowetting ew and electrowetting on dielectric ewod can be used to handle aqueous liquid in microscale without any second liquid medium. Characterization of the motion and mixing of droplets in. This has been termed electrowetting on line electrodes ele. Low voltage electrowettingondielectric for microfluidic systems. Highperformance reverse electrowetting energy harvesting.
Continuous optoelectrowetting for picoliter droplet manipulation p. Volume 95, issues 23, 1 january 2002, pages 259268. Ewod is a phenomenon where a voltage applied to a conducting liquid on a dielectric covered electrode causes. Oct 10, 2011 electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. Pdf basics and applications of electrowetting on dielectric ew. Magnetic bead manipulations in microfluidic devices paper. Dielectric breakdown and failure of ferroelectric films as. This paper discusses the modeling and simulation of a parallelplate electrowetting on dielectric ewod device that moves fluid droplets through surface tension effects. This phenomenon, known as electrowetting, consists in the spread of a liquid drop placed on an electrode upon application of a voltage. This paper reports the electrowetting ew properties of silica layers.
Ewod is used as onchip micropumping scheme for moving fluid digitally in labonachip devices. Emulsification, separation, and manipulation of oilwater. Extra vaporphase silane vps is introduced into the chamber and acts as an aerosol primer to enhance the chemical adhesion to the. We demonstrate that, using xps data, independent of the sign of the applied voltage, the droplet. Volume and concentration identification by using an. Continuous electrowetting at the low concentration electrolyteinsulatorsemiconductor junction.
The physical mechanism responsible for droplet manipulation in electrowetting on dielectric ewod devices is not yet fully understood. Electrowetting can be also employed to characterize the. 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. Due to the advantages of rapid response and the programmability of droplet movements, electrowetting on dielectric ewod ref. 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. Electrowetting electrowetting digital microfluidic circuit cho, sk, et al, creating, transporting, cutting and merging liquid droplets by electrowettingbased actuation for digital microfluidic circuits. Electrowetting on dielectric ewod properties of teflon. The surface roughness measurements revealed an increase in roughness with increasing electrospraying time. 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. Electrowetting on dielectric ewod device with dimple structures. Electrowetting on dielectric ewod on a digital microfluidic. Author links open overlay panel junghoon lee a hyejin moon b jesse fowler b thomas schoellhammer c changjin kim b. Pdf modeling the fluid dynamics of electrowetting on. Rewod with the ald al 2 o 3 thin films exhibited high performances under lowvoltage and.
In these cases, liquid is in direct contact with air. Water or aqueous electrolytes are the dominant components in electrowetting on dielectric ewodbased microfluidic devices. The alternative use of ionic liquids ils as electrowetting agents in ewodbased applications or. Electrowetting on this dielectriccoated surface is called electrowettingondielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. Floating electrode electrowetting on hydrophobic dielectric. Electrowetting has applications in electrowettingbased screens 8, vibration energy harvesters 9, lenses 10, and labonachip devices 1114. By modifying the previous work on mechanical filtration on ewod. Digital microfluidics is an alternative paradigm for labonachip systems based upon micromanipulation of discrete droplets. 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. Abstract a highly efficient and reliable electrowetting on dielectric ewod digital microfluidics dmf chip is proposed. Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the cytop surface, without electrical connection to the substrate.
Modeling the fluid dynamics of electrowetting on dielectric. All structured data from the file and property namespaces is available under the creative commons cc0 license. Thin nanocomposite dielectrics were spin casted from batio3 nanopowder dispersed in a. E electrowetting 601 electrowetting, figure 1 schematic illustration of the various electrode con. 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 labonachip and optical devices. Dispensing 300pl droplets from 140nl closed onchip reservoirs was accomplished with as little as 11. 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. Electrowetting has applications in electrowettingbased. 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. 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. Pdf low voltage electrowettingondielectric researchgate. Piezodriven acoustic streaming in an electrowettingon. 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.
Electrowettingondielectric actuation of a vertical translation. In many applications the solid surface consists of a thin dielectric deposited onto a conducting layer. Continuous optoelectrowetting for picoliter droplet. Electrowettingondielectric ewod based droplet actuation in microfluidic chip is designed and fabricated. 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.
Among printing technologies, the rreverseoffsetprinting rop method that can achieve high resolution and complicated shape patterns is utilized to fabricate the electrowettingon. Extra vaporphase silane vps is introduced into the chamber and acts as an aerosol. Digital microfluidics based on electrowetting on dielectric. Specifically, thin layers of al 2 o 3 about 100 nmthick were successfully formed by ald to obtain dense films with high capacitances. The characterization results show that pzt thin film can serve as the dielectric of ewod with a high dielectric constant and a great. In the fabricated system, the pcb is used as a substrate and is covered with plastic tape. In contrast to some of the fiber voas described above, our voa used a nonphotorefractive fiber, i.
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. Low voltage electrowettingondielectric platform using. The breakdown voltage depends on dc voltage polarity. Volume and concentration identification by using an electrowetting on dielectric device yiyan li, hongzhong li, and r. A fundamental study on electrowetting by traditional and. Pdf the shape of liquiddroplet on planar surfaces is mainly governed by resultant surface tension forces at the vapourliquidsolid boundary. Optical characterisation of a long period grating using liquid droplets on an electrowettingondielectric platform a. We model the fluid dynamics by using heleshaw type equations with a focus on including the relevant boundary phenomena. Electrowetting on this dielectric coated surface is called electrowetting on dielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. Electrowetting 2018 university of twente research information. Dec 15, 2015 in this project, a platform for the manipulation of droplets was developed and characterized. 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.
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