DOCSLIB.ORG

Recent Advances in Electrowetting Microdroplet Technologies

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Recent Advances in Electrowetting Microdroplet Technologies Chapter 4 Recent Advances in Electrowetting Microdroplet Technologies Robert W. Barber and David R. Emerson 4.1 Introduction The ability to handle small volumes of liquid, typically from a few picolitres (pL) to a few microlitres (mL), has the potential to improve the performance of complex chemical and biological assays [1–6]. The benefits of miniaturisation are well documented [7–9] and include smaller sample requirements, reduced reagent con- sumption, decreased analysis time, lower power consumption, lower costs per assay and higher levels of throughput and automation. In addition, miniaturisation may offer enhanced functionality that cannot be achieved in conventional macroscale devices, such as the ability to combine sample collection, analyte extraction, preconcentration, filtration and sample analysis onto a single microfluidic chip [10]. Microfluidics-based lab-on-a-chip devices have received considerable attention in recent years, and are expected to revolutionise clinical diagnostics, DNA and protein analysis and many other laboratory procedures involving molecular biology [11–13]. Currently, most lab-on-a-chip devices employ continuous fluid flow through closed microchannels. However, an alternative approach, which is rapidly gaining popularity, is to mani- pulate the liquid in the form of discrete, unit-sized microdroplets—an approach which is often referred to as digital microfluidics [14–18]. The use of droplet-based microfluidics offers many benefits over continuous flow systems; one of the main advantages is that the reaction or assay can be performed sequentially in a similar manner to traditional (macroscale) laboratory techniques. Consequently, a wide range of established chemical and biological protocols can be transferred to the micro-scale without the need to establish continuous flow protocols for the same reaction. In addition, droplet-based systems avoid many of the problems associated with single- phase microfluidics such as sample cross-contamination and diffusional dilution. R.W. Barber (*) • D.R. Emerson Centre for Microfluidics and Microsystems Modelling, STFC Daresbury Laboratory, Warrington WA4 4AD, UK e-mail: [email protected] P. Day et al. (eds.), Microdroplet Technology: Principles and Emerging 77 Applications in Biology and Chemistry, Integrated Analytical Systems, DOI 10.1007/978-1-4614-3265-4_4, # Springer Science+Business Media, LLC 2012 78 R.W. Barber and D.R. Emerson One of the most important consequences of miniaturisation is the increase in the surface-to-volume ratio of the fluid. For example, the surface-to-volume ratio for a device with a characteristic length of 1 m is of order 1 mÀ1 whilst the surface-to- volume ratio for a microfluidic device having a characteristic length of 1 mm will increase to 106 mÀ1. In other words, the surface-to-volume ratio of the fluid scales according to the inverse of the characteristic length [8]. Consequently, as devices are reduced in size, inertial forces will decrease while viscous effects and surface energies will become increasingly important. In the case of submillimetre- sized liquid droplets, capillary forces dominate the motion [19]. Under these circumstances, the control of the surface energy provides a useful tool for manipulating droplets [20–23]. Although chemical and topographical patterning of substrates has received considerable attention in recent years [24–26], the static nature of these surface treatments prevents the active control of droplets, as required in a fully-controllable digital microfluidic system. As a consequence, considerable work has been dedicated to the development of techniques that allow the wettability of the substrate to be varied both spatially and temporally. The most promising droplet actuation technique for digital microfluidic applications appears to be electrowetting [27–32], although other mechanisms have been demonstrated including dielectrophoresis [33–35], thermocapillary actuation [36–38] and optoelectrowetting [39–43]. In addition, other promising droplet handling techniques such as surface acoustic wave (SAW) actuation have been developed [44–47] although in this case, the droplet movement is achieved via the creation of acoustic waves rather than by changing the wettability of the surface. Furthermore, electrowetting can be combined with electrophoresis/dielectrophoresis, to provide a method for particle separation or sample enrichment [48–51], or can be used to collect or separate magnetic particles [52–54]. Over the last few years, electrowetting has become an increasingly important technology for droplet manipulation. Electrowetting can commonly achieve contact angle variations of more than 40 and the switching cycles can be performed hundreds of thousands of times without any detrimental effects to either the fluid or the chip. The switching response time for millimetre-sized droplets is relatively fast (typically several milliseconds) and is only limited by the inertia of the droplet rather than the switching time of the equilibrium contact angle [31]. Within just a few years, a rapidly expanding community of researchers has taken the concept of electrowetting from the initial research stage into fully-integrated digital microfluidic devices that are capable of complex chemical and biological assays [55–57]. 4.2 Theory of Electrowetting The phenomenon of electrocapillarity (or electrowetting) was first described by Lippmann [58] in 1875 when he showed that the capillary depression of mercury in contact with an electrolyte solution could be controlled by the application of a voltage. 4 Recent Advances in Electrowetting Microdroplet Technologies 79 As well as formulating the basic theory for electrocapillarity, he also proposed several practical devices that made use of the phenomenon, including a very sensitive electrometer which was later used to record the world’s first electrocardiogram (ECG). Unfortunately, the application of electrowetting to aqueous electrolytes is severely restricted due to the electrolytic decomposition of water beyond a few hundred millivolts. In the 1990s, however, Berge [59] and Vallet et al. [60]realised that the problem of electrolysis could be overcome by the introduction of a thin insulating layer to separate the conductive liquid from the metal electrode. This concept is nowadays referred to as electrowetting-on-dielectric (EWOD) [61]or electrowetting-on-insulator-coated-electrodes (EICE) [28] and involves applying a voltage to modify the wetting behaviour of a conductive liquid in contact with a hydrophobic, insulated electrode. Thorough descriptions of electrowetting have been published by Mugele and Baret [31], Berthier [62] and Berthier and Silberzan [63] whilst investigations into the types of liquids that can be transported by EWOD have been conducted by Pollack [64], Srinivasan [65] and Chatterjee et al. [66]. In most practical electrowetting applications, the droplets reside on a hori- zontal planar substrate and are usually composed of aqueous solutions with a typical droplet diameter of 1 mm or less. The medium surrounding the droplet can either be air or another immiscible liquid such as silicone oil. However, recent work by Brassard et al. [67] has shown that it is possible to use an alternative mode of operation where the aqueous droplet is enclosed in a thin layer of oil which in turn is surrounded by air; this technique is referred to as water-oil core-shell droplets. The relative importance of the gravitational force to the surface tension force can 2 be expressed by the Bond number [62], Bo ¼ DrgR =slv where Dr is the difference in density between the droplet and the surrounding medium, g is the acceleration due to gravity, R is the radius of curvature of the droplet, and slv is the liquid-vapour surface tension. (The Bond number is sometimes referred to as the Eotv€ os€ number, Eo.) In most electrowetting applications, the Bond number is usually less than unity [62], implying that gravitational forces are small in comparison to the surface tension force; it is therefore appropriate to ignore gravity in electrowetting applications [31]. In the absence of an external electric field, the shape of the droplet is determined solely by the surface tension, according to standard equilibrium theory (Young’s equation) [62]. As shown in Fig. 4.1a, a surface tension (a force per unit length or an energy per unit area) is associated with the interface between each of the three phases; the solid substrate (s), the liquid droplet (l) and the surrounding ambient phase, which for simplicity is often denoted as vapour (v). Each interface exerts a force on the three-phase contact line, and the balance between the interfacial surface tensions i.e. ssv (solid-vapour), ssl (solid–liquid) and slv (liquid-vapour) must be in equilibrium: ssv À ssl À slv cos yeq ¼ 0 (4.1) 80 R.W. Barber and D.R. Emerson Fig. 4.1 A schematic diagram of wetting and electrowetting. (a) In the absence of an external electric field, the sum of the forces along the three-phase contact line must balance, leading to an equilibrium contact angle, yeq.(b) Application of a potential difference between the liquid and the substrate creates a capacitance, C, at the solid–liquid interface which causes the solid–liquid interfacial surface tension to be reduced by CV2=2. This causes the droplet to spread and reduces the contact angle to yEW where yeq is the equilibrium (or Young’s) contact angle. Rearranging (4.1) yields the familiar form of Young’s equation: ssv À ssl cos yeq ¼ (4.2) slv It should be noted that the vertical component of the surface tension force is balanced by normal stresses within the solid substrate [31]. Applying a potential difference, V, between the liquid and the substrate will change the shape of the droplet, as shown schematically in Fig. 4.1b. This is due to the fact that the solid–liquid interface effectively behaves as a parallel-plate capacitor, with a capacitance per unit area, C. The energy stored in the capacitor is CV2=2 whilst the work done by the external supply voltage is À CV2 and therefore the free energy of the droplet per unit interfacial area is reduced by CV2=2.
Load more

Recommended publications
  • Digital Microfluidic Devices: the Role of the Dielectric Layer
    Vasco Alexandre Violante Rodrigues Licenciatura em Ciências de Engenharia em Micro e Nanotecnologias Digital Microfluidic devices: the role of the dielectric layer Dissertação para obtenção do Grau de Mestre em Engenharia de Micro e Nanotecnologias Orientador: Professor Doutor Rui Igreja, Dep. Ciência dos Materiais, FCT-UNL Co -orientador: Professor Doutor Hugo Águas, Dep. Ciência dos Materiais, FCT-UNL Júri: Presidente: Prof. Doutor Rodrigo Ferrão de Paiva Martins Arguente: Doutora Rita Maria Mourão Salazar Branquinho Vogal: Prof. Doutor Rui Alberto Garção Barreira do Nascimento Igreja Novembro, 2014 DIGITAL MICROFLUIDICS: THE ROLE OF THE DIELECTRIC LAYER © Vasco Alexandre Violante Rodrigues Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa A Faculdade de Ciências e Tecnologia e a Universidade Nova de Lisboa têm o direito, perpétuo e sem limites geográficos, de arquivar e publicar esta dissertação através de exemplares impressos reproduzidos em papel ou de forma digital, ou por qualquer outro meio conhecido ou que venha a ser inventado, e de a divulgar através de repositórios científicos e de admitir a sua cópia e distribuição com objectivos educacionais ou de investigação, não comerciais, desde que seja dado crédito ao autor e editor. AGRADECIMENTOS É com enorme satisfação que vejo cumprida mais uma etapa da minha vida, tendo sido esta porventura uma das mais exigentes até ao momento. A conclusão deste trabalho encerra em si um capítulo que começou por ser caracterizado por grande incerteza, tendo eu pertencido ao reduzido grupo de pessoas que ingressou pela primeira vez no Mestrado Integrado em Engenharia de Micro e Nanotecnologias, e é com alegria que pertenço ao grupo ainda mais restrito de pessoas que o conclui agora, cinco anos volvidos.
    [Show full text]
  • Recent Advances in Droplet-Based Microfluidic Technologies
    micromachines Review Recent Advances in Droplet-based Microfluidic Technologies for Biochemistry and Molecular Biology 1, 1, 2, Joel Sánchez Barea y , Juhwa Lee y and Dong-Ku Kang * 1 Department of Chemistry, Incheon National University, Incheon 22012, Korea; [email protected] (J.S.B.); [email protected] (J.L.) 2 Department of Chemistry, Research Institute of Basic Sciences, Incheon National University, Incheon 22012, Korea * Correspondence: [email protected]; Tel.: +82-32-835-8094 These authors contribute equally to this article. y Received: 2 May 2019; Accepted: 18 June 2019; Published: 20 June 2019 Abstract: Recently, droplet-based microfluidic systems have been widely used in various biochemical and molecular biological assays. Since this platform technique allows manipulation of large amounts of data and also provides absolute accuracy in comparison to conventional bioanalytical approaches, over the last decade a range of basic biochemical and molecular biological operations have been transferred to drop-based microfluidic formats. In this review, we introduce recent advances and examples of droplet-based microfluidic techniques that have been applied in biochemistry and molecular biology research including genomics, proteomics and cellomics. Their advantages and weaknesses in various applications are also comprehensively discussed here. The purpose of this review is to provide a new point of view and current status in droplet-based microfluidics to biochemists and molecular biologists. We hope that this review will accelerate communications between researchers who are working in droplet-based microfluidics, biochemistry and molecular biology. Keywords: droplet-based microfluidic; biochemistry; molecular biology; digital PCR; biochip; biosensor; digital quantification; microfluidic; single cell analysis 1.
    [Show full text]
  • Opto-Electrowetting (OEW)
    Nano-Bio-Sens ing Summer Sc hoo l @ EPFL June 29 – July 3, 2009 Introduction to Optofluidics Ming C. Wu University of California, Berkeley Electrical Engineering & Computer Sciences Dept. Berkeley Sensor and Actuator Center (BSAC) [email protected] .edu Wu-1 ©2009. University of California Optofluidics • Electrowetting optics • Tunable lenses • Electronic papers • Optical trapping and manipulation • Optofluidic lab-on-a-chip • Microresonators • Photonic crystals Wu-2 ©2009. University of California Optofluidics • Integration of optics and fluidics to synthesize novel functionalities • Applications: Li, et. al., Opt. Express, 2006 – Use microfluidics to control light • Optical switches, tunable lenses • Display • Sensors – Use light t o cont rol micro flu idics, micro/nanoparticles, cells, … Wolfe, et. al., Proc. Natl. Acad. Sci. , 2004 • Optical trapping, sorting, and assembly • Non-invasive optical actuation Psaltis, et. al., Nature, 2006 Domachuck, et. al., Nature, 2005 Wu-3 ©2009. University of California “Bubble” Switches Agilent Champaign Switch • Optical crossbar switch using total internal reflection by a thermally generated bubble • 32x32 switches have been demonstrated • J. E. Fouquet, "Compact optical cross-connect switch based on total internal reflection in a fluid- containing planar lightwave circuit,“ OFC 2006 Wu-4 ©2009. University of California Optofludic Microscopy • Low-cost, high-resolution (0.8 !m), lensless on-chip microscopes • Use micro flu idic flow to de liver specimens across apertures on a metal-coated CMOS sensor X. Cui, L. M. Lee, X. Heng, W. Zhong, P. W. Sternberg, D. Psaltis, and C. Yang, "Lensless high-resolution on-chip optofluidic microscopes for Caenorhabditis elegans and cell imaging," Proceedings of the National Academy of Sciences, vol.
    [Show full text]
  • Detection of Dna Hybridization on a Configurable Digital Microfluidic
    DETECTION OF DNA HYBRIDIZATION ON A CONFIGURABLE DIGITAL MICROFLUIDIC BIO- CHIP USING SPR IMAGING Lidija Malic1, Teodor Veres2 and Maryam Tabrizian1 1Biomedical Engineering Department, McGill University, CANADA and 2Industrial Materials Institute, National Research Council, CANADA ABSTRACT This paper presents a configurable digital microfluidic-based surface plasmon resonance (SPR) biochip platform comprising an electrowetting-on-dielectric (EWOD) microfluidic device coupled to SPR imaging (SPRi). We demonstrate its application for dynamic on-chip simultaneous immobilization of different DNA probes in combination with multichannel label-free real-time detection of subse- quent hybridization reactions. The integrated EWOD-SPRi system would enable the development of high-throughput, rapid and ultrasensitive biomolecular detection strategies beyond DNA microarray applications. KEYWORDS: Digital microfluidics, EWOD, SPR imaging, DNA hybridization INTRODUCTION EWOD microfluidics has attracted considerable attention in the past decade and the most recent efforts are directed towards its application in biomedical research [1- 3]. While these studies demonstrate the versatility of EWOD devices, the reported applications involve homogeneous phase reactions [4] and detection methods that require labeled biomolecules [2] or sample extraction from the chip [1]. This in- creases both the time and complexity of the assay. To introduce new applications relying on label-free, real-time surface sensitive detection techniques such as SPRi, it would be advantageous to use droplet-based EWOD actuation for surface specific biomolecule immobilization. However, the need of hydrophobic properties for EWOD actuation renders immobilization of biomolecules such as DNA on the sur- face of the chip impossible [3, 4]. In this paper, we demonstrate for the first time the use of an EWOD microfluidic chip to dynamically immobilize DNA probes in a two-dimensional array, followed by SPRi detection of bioaffinity interactions.
    [Show full text]
  • Combining Electrowetting and Magnetic Bead Manipulations for Use in Microfluidic Immunoassays
    Combining Electrowetting and Magnetic Bead Manipulations for Use in Microfluidic Immunoassays Amanda Barbour Ronit Langer [email protected] [email protected] Tiffany Li Katherine Tsang [email protected] [email protected] Rose Yin [email protected] Abstract afford to lose large amounts of blood.1 It This experiment investigated reducing the also takes 2 days of incubation time, which cost of microfluidic immunoassays. places a risk on patients with urgent health Magnetic microbeads are used in these concerns.1 Technologies in microfluidics assays to increase the efficiency of have created a different type of immunoassays, but they also raise the cost. immunoassay that uses magnetic This experiment aims to reduce the number microbeads. It can be performed within of magnetic beads necessary by using minutes with only 5-10 µL of blood, making electrowetting in conjunction with the beads. it safer for patients who cannot afford to lose Single and parallel plate electrowetting blood, and more efficient for doctors.2 devices were tested individually and the However, this process is very expensive due magnetic microbeads. The devices did not to the large number of microbeads needed. succeed in separating the beads from the During the assay, the microbeads need to be droplets, but the results show many separated from each sample and pulled promising options for further investigation. through microchannels into a new solution. In order to separate, the microbeads need to 1. Introduction break the surface tension of the sample, and 3 With the increasing pace of today’s society, this requires thousands of microbeads. current medicine requires fast and accurate This project aims to create a method diagnoses for patients.
    [Show full text]
  • Towards Automated Optoelectrowetting on Dielectric Devices for Multi-Axis Droplet Manipulation
    2013 IEEE International Conference on Robotics and Automation (ICRA) Karlsruhe, Germany, May 6-10, 2013 Towards Automated Optoelectrowetting on Dielectric Devices for Multi-Axis Droplet Manipulation Vasanthsekar Shekar, Matthew Campbell, and Srinivas Akella Abstract— Lab-on-a-chip technology scales down multiple layout of electrodes, and layout design restrictions arising laboratory processes to a chip capable of performing automated from electrode addressing constraints. We can overcome biochemical analyses. Electrowetting on dielectric (EWOD) is a these limitations by light-actuated droplet manipulation. digital microfluidic lab-on-a-chip technology that uses patterned electrodes for droplet manipulation. The main limitations of EWOD devices are the restrictions in volume and motion of Optoelectrowetting (OEW) is a light-actuated droplet ma- droplets due to the fixed size, layout, and addressing scheme of nipulation technique using optical sources and electric fields. the electrodes. Optoelectrowetting on dielectric (OEWOD) is a A projected pattern of light, which acts as a virtual electrode, recent technology that uses optical sources and electric fields for is moved to manipulate the droplet. The optical source droplet actuation on a continuous surface. We describe an open surface light–actuated OEWOD device that can manipulate generating the patterns ranges from a laser [6] to an LCD droplets of multiple volumes ranging from 1 to 50 µL at screen [7]. The main advantages of OEW devices are the voltages below 45 V. To achieve lower voltage droplet actuation simplicity in fabrication process and the large continuous than previous open configuration devices, we added a dedicated droplet manipulation region compared to EWOD devices. dielectric layer of high dielectric constant (Al2O3 with εr of 9.1) Devices that use OEW on a dielectric surface for droplet and significantly reduced the thickness of the hydrophobic layer.
    [Show full text]
  • Demonstration of Automated DNA Assembly on a Digital Microfluidic Device
    Rochester Institute of Technology RIT Scholar Works Theses 5-12-2021 Demonstration of Automated DNA Assembly on a Digital Microfluidic Device Hee Tae An [email protected] Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation An, Hee Tae, "Demonstration of Automated DNA Assembly on a Digital Microfluidic Device" (2021). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. ROCHESTER INSTITUTE OF TECHNOLOGY ROCHESTER, NY Demonstration of Automated DNA Assembly on a Digital Microfluidic Device by Hee Tae An A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Microelectronic Engineering Submitted May 12, 2021 DEPARTMENT OF ELECTRICAL AND MICROELECTRONIC ENGINEERING KATE GLEASON COLLEGE OF ENGINEERING Approved By: Dr. Michael Schertzer, Associate Professor Date Thesis Advisor, Department of Mechanical Engineering Dr. Karl Hirschman, Professor Date Committee Member, Department of Electrical and Microelectronic Engineering Dr. Ivan Puchades, Assistant Professor Date Committee Member, Department of Electrical and Microelectronic Engineering Dr. Michael Schrlau, Associate Professor Date Committee Member, Department of Mechanical Engineering Dr. Sean Rommel, Director of Microelectronic Engineering/Professor Date Department Representative, Department of Electrical and Microelectronic Engineering Abstract The rapid manufacturing of highly accurate synthetic DNA is crucial for its use as a molec- ular tool, the understanding and engineering of regulatory elements, protein engineering, genetic refactoring, engineered genetic networks and metabolic pathways, and whole-genome syntheses [1,2].
    [Show full text]
  • Protein Stamping for Maldi Mass Spectrometry Using an Electrowetting-Based Microfluidic Platform
    PROTEIN STAMPING FOR MALDI MASS SPECTROMETRY USING AN ELECTROWETTING-BASED MICROFLUIDIC PLATFORM Vijay Srinivasan1, Vamsee Pamula, Phil Paik, and Richard Fair Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708-0291. ABSTRACT MALDI-MS (matrix-assisted laser desorption/ionization mass spectrometry) is one of the most commonly used tech- niques for protein analysis. In conventional systems sample preparation is typically done in well-plates and transferred onto a MALDI target by robotic systems, which are complex, huge, expensive and slow. In this paper, we present a droplet-based microfluidic interface to transfer protein samples from a well-plate format onto a MALDI target for MS analysis. The droplets are actuated using the electrowetting phenomenon, and are immersed in silicone oil which pre- vents non-specific adsorption and enables the manipulation of high concentrations of proteins. Droplet transport and droplet formation were evaluated as a function of protein concentration using bovine serum albumin (BSA) as a test system. Droplet transport was possible for BSA concentrations up to 10mg/mL which is three orders of magnitude higher than previously reported results on handling proteins by electrowetting. Droplet formation from on-chip reser- voirs, using only electrowetting forces and no external pressure assistance, was possible up to concentrations of 0.01mg/mL. An interface between a well-plate format and the electrowetting chip, and a scheme to passively stamp droplets onto a target substrate was then designed and tested by stamping BSA solutions. In two separate experiments 3.6fmoles and 16fmoles of BSA were stamped onto a glass slide using 0.001mg/mL and 0.01mg/mL samples respec- tively.
    [Show full text]
  • Interfacing Microfluidics to LDI-MS by Automatic Robotic Spotting
    Microfluid Nanofluid (2010) 8:777–787 DOI 10.1007/s10404-009-0510-x RESEARCH PAPER Interfacing microfluidics to LDI-MS by automatic robotic spotting Chia-Wen Tsao • Song Tao • Chien-Fu Chen • Jikun Liu • Don L. DeVoe Received: 30 July 2009 / Accepted: 23 September 2009 / Published online: 13 October 2009 Ó Springer-Verlag 2009 Abstract We developed a method of interfacing micro- Keywords Mass spectrometry interfacing Á fluidics with mass spectrometry (MS) using a robotic Microfluidics Á Robotic spotting Á LDI-MS spotting system to automate the contact spotting process. We demonstrate that direct and automated spotting of analyte from multichannel microfluidic chips to a custom 1 Introduction microstructured MALDI target plate was a simple, robust, and high-throughput method for interfacing parallel The ability to perform high-throughput bioanalysis in a microchannels using matrix-assisted laser desorption/ioni- single integrated platform is a substantial benefit offered by zation mass spectrometry (MALDI-MS). Using thermo- microfluidics technology. Arrays of multiplexed micro- plastic cyclic olefin copolymer (COC) polymer microfluidic channels allowing large numbers of simultaneous on-chip chips containing eight parallel 100 lm 9 46 lm micro- analyses have been demonstrated in numerous applications channels connected to a single input port, spotting volume including chemical reaction screening (Wang et al. 2006a), repeatability and MALDI-MS signal uniformity are evalu- immunoassays (Wang et al. 2006b), enzymatic processing ated for a panel of sample peptides. The COC microfluidic (Su et al. 2005), biomolecular separations performed by chips were fabricated by hot embossing and solvent bond- zone electrophoresis (Chen et al. 2002; Shen et al.
    [Show full text]
  • Digital Microfluidics
    Microfluid Nanofluid DOI 10.1007/s10404-007-0161-8 REVIEW Digital microfluidics: is a true lab-on-a-chip possible? R. B. Fair Received: 10 February 2007 / Accepted: 14 February 2007 Ó Springer-Verlag 2007 Abstract The suitability of electrowetting-on-dielectric elemental operations, such as transport, mixing, or dis- (EWD) microfluidics for true lab-on-a-chip applications is pensing. These elemental operations are performed on an discussed. The wide diversity in biomedical applications elemental set of components, such as electrode arrays, can be parsed into manageable components and assembled separation columns, or reservoirs. Examples of the incor- into architecture that requires the advantages of being poration of these principles in complex biomedical appli- programmable, reconfigurable, and reusable. This capa- cations are described. bility opens the possibility of handling all of the protocols that a given laboratory application or a class of applications Keywords Lab-on-a-chip Á Digital microfluidics Á would require. And, it provides a path toward realizing the Biomedical applications Á Detection Á Analysis Á true lab-on-a-chip. However, this capability can only be Electrowetting realized with a complete set of elemental fluidic compo- nents that support all of the required fluidic operations. Architectural choices are described along with the reali- 1 Introduction zation of various biomedical fluidic functions implemented in on-chip electrowetting operations. The current status of Historically, microfluidic devices have been designed from this EWD toolkit is discussed. However, the question re- the bottom up, whereby various fluidic components are mains: which applications can be performed on a digital combined together to achieve a device that performs a microfluidic platform? And, are there other advantages particular application.
    [Show full text]
  • (EWOD): Current Perspectives and Applications in Ensuring Food Safety
    Volume 28 Issue 4 Article 8 2020 Electrowetting-on-dielectric (EWOD): Current perspectives and applications in ensuring food safety Follow this and additional works at: https://www.jfda-online.com/journal Part of the Food Science Commons, Medicinal Chemistry and Pharmaceutics Commons, Pharmacology Commons, and the Toxicology Commons This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License. Recommended Citation Barman, Snigdha Roy; Khan, Imran; Chatterjee, Subhodeep; Saha, Subhajit; Choi, Dukhyun; Lee, Sangmin; and Lin, Zong-Hong (2020) "Electrowetting-on-dielectric (EWOD): Current perspectives and applications in ensuring food safety," Journal of Food and Drug Analysis: Vol. 28 : Iss. 4 , Article 8. Available at: https://doi.org/10.38212/2224-6614.1239 This Review Article is brought to you for free and open access by Journal of Food and Drug Analysis. It has been accepted for inclusion in Journal of Food and Drug Analysis by an authorized editor of Journal of Food and Drug Analysis. Electrowetting-on-dielectric (EWOD): Current perspectives and applications in ensuring food safety REVIEW ARTICLE Snigdha Roy Barman a, Imran Khan b, Subhodeep Chatterjee c, Subhajit Saha a, Dukhyun Choi d,**, Sangmin Lee e,***, Zong-Hong Lin a,c,d,* a Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan b Institute of NanoEngineering and Microsystems, National Tsing Hua University, Hsinchu 30013, Taiwan c Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan d Department of Mechanical Engineering, Kyung Hee University, Yongin, 17104, South Korea e School of Mechanical Engineering, Chung-Ang University, Seoul 06974, South Korea Abstract Digital microfluidic (DMF) platforms have contributed immensely to the development of multifunctional lab-on-chip systems for performing complete sets of biological and analytical assays.
    [Show full text]
  • Fundamentals and Applications of Electrowetting: a Critical Review
    Fundamentals and Applications of Electrowetting: A Critical Review Ya-Pu Zhao* and Ying Wang State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics Chinese Academy of Sciences, Beijing 100190, China Abstract: We have witnessed rapid and exciting development in electrowetting (EW) or electrowetting-on-dielectric (EWOD) since 1990s. Owing to its great advantages such as easy operation, sensitive response and electrical reversibility, EW has found many applications in various fi elds, especially in micro- and nano-fl uidics, electronic display, etc. The aim of this review is to inspire new investigations on EW, not only in theory and numerical simulation, but also in experiments, and spur further research on EW for more practical applications. A comprehensive review is presented on the EW research progress, and experiments, theoretical modeling and numerical simulations are covered. After a brief look at the development history, some latest experimental and simulation methods, such as Lattice Boltzmann method, phase-fi eld method and molecular dynamics (MD), are introduced. Some representative practical applications are then presented. Unresolved issues and prospects on EW as the fi nal part of this review are expected to attract more attention and inspire more in-depth studies in this fascinating area. Keywords: Electrowetting (EW), electrowetting-on-dielectric (EWOD), Lippmann- Young (L-Y) equation, curvature effect, elasto-electro-capillarity (EEC), Lattice Boltzmann method (LBM), phase-fi eld model, molecular dynamics (MD) simulations, coffee stain ring, electronic display, liquid lens, Micro Total Analysis Systems (μ-TAS), cell-based digital microfl uidics 1 Motivation Electrowetting (EW) or electrowetting-on-dielectric (EWOD) is an indispensable and versatile means for droplet manipulation.
    [Show full text]