Electrowetting on dielectric ewod on a digital microfluidic. Emulsification, separation, and manipulation of oilwater. For many materials systems used in ew structures, ca saturation is observed at. The pzt thin film is formed by spincoating, pyrolysis and annealing. 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. 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. 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 can be demonstrated by replacing the metal.
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. Continuous electrowetting at the low concentration electrolyteinsulatorsemiconductor junction. Extra vaporphase silane vps is introduced into the chamber and acts as an aerosol primer to enhance the chemical adhesion to the. 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.
Electrowetting using an insulating layer on top of a bare electrode was later studied by bruno berge in 1993. Magnetic bead manipulations in microfluidic devices paper. Accurate, consistent, and fast droplet splitting and. Modeling and characterization of an electrowetting based. 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. 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.
Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the cytop surface, without electrical connection to the substrate. Electrowetting electrowetting digital microfluidic circuit cho, sk, et al, creating, transporting, cutting and merging liquid droplets by electrowettingbased actuation for digital microfluidic circuits. 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. 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. Modeling the fluid dynamics of electrowetting on dielectric ewod article pdf available in journal of microelectromechanical systems 154. 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 on this dielectriccoated surface is called electrowettingondielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. Electrowetting uses voltage to manipulate small volumes of fluid for applications including lab on achip and optical devices. Electrowetting uses voltage to manipulate small volumes of fluid for applications including labonachip and optical devices. Micro and nano syst lett accurate, consistent, and fast droplet splitting and dispensing in electrowetting on dielectric digital microfluidics n. This paper reports the electrowetting ew properties of silica layers. Dc electrowetting of nonaqueous liquid revisited by xps. We model the fluid dynamics by using heleshaw type equations with a focus on including the relevant boundary phenomena. In this paper, the dielectric and electrowetting properties of pb zr 0.
Optical characterisation of a long period grating using liquid droplets on an electrowettingondielectric platform a. Volume 95, issues 23, 1 january 2002, pages 259268. This investigation will examine the role of capillary forces on droplet manipulation to further the physical understanding of these devices. Optical characterisation of a long period grating using.
In contrast to some of the fiber voas described above, our voa used a nonphotorefractive fiber, i. Water or aqueous electrolytes are the dominant components in electrowetting on dielectric ewodbased microfluidic devices. Electrowetting on dielectric ewod based droplet actuation in microfluidic chip is designed and fabricated. Specifically, thin layers of al 2 o 3 about 100 nmthick were successfully formed by ald to obtain dense films with high capacit. Electrowetting on dielectric ewod has previously been used to modify the. Electrowetting,applications, figure 6 illustrationof thesoft printing process. Among printing technologies, the rreverseoffsetprinting rop method that can achieve high resolution and complicated shape patterns is utilized to fabricate the electrowettingon. In this paper, the dielectric and electrowetting properties of pb zr0. In the fabricated system, the pcb is used as a substrate and is covered with plastic tape. 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. Low voltage electrowettingondielectric article pdf available in journal of applied physics 927 october 2002 with 2,764 reads how we measure reads.
The breakdown voltage depends on dc voltage polarity. This has been termed electrowetting on line electrodes ele. A significant contact angle change 12080 is desired to reliably pump the droplet in microchannels for applications such as labonachip or micrototal analysis systems. In cases where the insulating layer is not hydrophobic e. Electrowetting can be also employed to characterize the. By modifying the previous work on mechanical filtration on ewod. This phenomenon, known as electrowetting, consists in the spread of a liquid drop placed on an electrode upon application of a voltage.
Electrowetting on dielectric ewod properties of teflon. Electrowetting has applications in electrowettingbased screens 8, vibration energy harvesters 9, lenses 10, and labonachip devices 1114. Strong charge trapping and bistable electrowetting on. Pdf basics and applications of electrowetting on dielectric ew. Floating electrode electrowetting on hydrophobic dielectric with an sio 2 layer mehdi khodayari, benjamin hahne, nathan b. Digital microfluidics based on electrowetting on dielectric. We demonstrate that, using xps data, independent of the sign of the applied voltage, the droplet. 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. Pdf the shape of liquiddroplet on planar surfaces is mainly governed by resultant surface tension forces at the vapourliquidsolid boundary.
In this project, a platform for the manipulation of droplets was developed and characterized. Low voltage electrowettingondielectric for microfluidic systems. The motion of a conductive liquid on a dielectriccoated conductive substrate has been extensively studied in the past as a part of electrowettingondielectric. Ac electrowetting modulation of lowvolatile liquids. Pdf low voltage electrowettingondielectric researchgate. Dielectric breakdown and failure of ferroelectric films as. The alternative use of ionic liquids ils as electrowetting agents in ewodbased applications or. Electrowetting and electrowettingondielectric for microscale liquid handling. Electrowetting based devices flourished upon the discovery that an added dielectric layer between the drop and a conductive electrode would tolerate the application of. Electrowetting on dielectric ewod discrete microfluidic dmf devices have shown favorable properties for use in microreactor labonachip applications. This paper discusses the modeling and simulation of a parallelplate electrowetting on dielectric ewod device that moves fluid droplets through surface tension effects. Characterization of the motion and mixing of droplets in. Electrowetting on this dielectric coated surface is called electrowetting on dielectric ewod to distinguish it from the conventional electrowetting on the bare electrode. Thin nanocomposite dielectrics were spin casted from batio3 nanopowder dispersed in a.
Low voltage electrowettingondielectric for microfluidic. Continuous optoelectrowetting for picoliter droplet. Ewod is used as on chip micropumping scheme for moving fluid digitally in lab on achip devices. Modeling the fluid dynamics of electrowetting on dielectric.
Using ferroelectric thin film as the dielectric for. 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. In this paper, we study the electrical properties and breakdown phenomena of pzt ferroelectric thin film in electrowetting systems. For enabling this scheme, stacked deposition of thin dielectric and hydrophobic layer in that order between microchannel and electrodes is done.
Automated droplet manipulation through electrowetting on. Electrowetting 2018 university of twente research information. Volume and concentration identification by using an electrowetting on dielectric device yiyan li, hongzhong li, and r. 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. In general, the term electrowetting, at least for ewod or. Electrowetting on dielectric ewod device with dimple structures. Highperformance reverse electrowetting energy harvesting.
It is important to note that no materials optimization was performed to. Abstract a highly efficient and reliable electrowetting on dielectric ewod digital microfluidics dmf chip is proposed. Spontaneous electrowetting, in contrast, can arise using the parallel line electrode con. Charge injection in dielectric films during electrowetting actuation under direct current voltage.
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 without external voltage using painton. Digital microfluidics is an alternative paradigm for labonachip systems based upon micromanipulation of discrete droplets. In these cases, liquid is in direct contact with air. Reverse electrowetting as a new approach to highpower. This dependence of applied voltage on dielectric thickness is confirmed through ewod experiments for three different dielectric materials of. Ewod is a phenomenon where a voltage applied to a conducting liquid on a dielectric covered electrode causes. This surface configuration coupled with the use of a highk dielectric drastically reduces the voltage required to induce electrocoalescence. Furthermore, electrowetting optics pose a greater fabrication challenge than optofluidic devices, which often rely on bulky peripherals such as syringe pumps. October 2, 2002 the electrowetting phenomenon is investigated in the viewpoint of the. Electrowetting on dielectric experiments using graphene. Volume and concentration identification by using an. 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.
Materials in mems springer, berlin, heidelberg, 20, p. Design and fabrication of printed electrowettingon. The surface roughness measurements revealed an increase in roughness with increasing electrospraying time. Uttamchandania a department of electronic and electrical engineering, university of strathclyde, glasgow, g1 1xw, uk. Ultralowvoltage electrowetting the journal of physical. 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. 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. Electrowettingbased actuation of liquid droplets for microfluidic applications. Ion and liquid dependent dielectric failure in electrowetting systems. 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. A highly efficient and reliable electrowetting on dielectric. Pdf modeling the fluid dynamics of electrowetting on. Electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. Electrowetting has applications in electrowettingbased.
All structured data from the file and property namespaces is available under the creative commons cc0 license. Specifically, thin layers of al 2 o 3 about 100 nmthick were successfully formed by ald to obtain dense films with high capacitances. 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. The physical mechanism responsible for droplet manipulation in electrowetting on dielectric ewod devices is not yet fully understood. Electrowettingondielectric actuation of a vertical translation. A fundamental study on electrowetting by traditional and.
Extra vaporphase silane vps is introduced into the chamber and acts as an aerosol. Dec 15, 2015 in this project, a platform for the manipulation of droplets was developed and characterized. Electrowettingondielectric ewod based droplet actuation in microfluidic chip is designed and fabricated. Ewod is used as onchip micropumping scheme for moving fluid digitally in labonachip devices. An 8 m parylene c layer is used as the dielectric material. 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.
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. The characterization results show that pzt thin film can serve as the dielectric of ewod with a high dielectric constant and a great. E electrowetting 601 electrowetting, figure 1 schematic illustration of the various electrode con. Continuous optoelectrowetting for picoliter droplet manipulation p. Electrowetting ew and electrowetting on dielectric ewod can be used to handle aqueous liquid in microscale without any second liquid medium.
Low voltage electrowettingondielectric platform using. Rewod with the ald al 2 o 3 thin films exhibited high performances under lowvoltage and. Electrowetting on dielectric driven droplet resonance and. 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. Oct 10, 2011 electrowetting on dielectrics for manipulating oil drops and gas bubbles in aqueousshell compound d duration. Electrowetting, applications 607 spontaneous electrowetting, on the other hand, arises when a thin frontrunning electrowetting. 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. One of the roles of the magnetic beads in the immunoassay is to break the. A low voltage, twolevelmetal, and multilayer insulator electrowettingondielectric ewd platform is presented. In many applications the solid surface consists of a thin dielectric deposited onto a conducting layer. Low thermal stability, evaporation, and a propensity to facilitate corrosion of the metal parts of integrated circuits or electronics are drawbacks of aqueous solutions.