DOCSLIB.ORG

Active Electrokinetic Transport Control in a Nanofluidic Device with Embedded Surface

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Active Electrokinetic Transport Control in a Nanofluidic Device with Embedded Surface Active Electrokinetic Transport Control in a Nanofluidic Device with Embedded Surface Electrodes DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Marie J. Fuest Graduate Program in Mechanical Engineering The Ohio State University 2016 Dissertation Committee: Professor Shaurya Prakash “Advisor” Professor Carlos Castro Professor A.T. Conlisk Professor Steven Ringel Copyright by Marie J. Fuest 2016 Abstract Since the 1990s, lab-on-a-chip (LoC) systems, or miniaturized devices that perform several unit operations that typically require bench top sized equipment on an integrated platform have been developed for applications in biotechnology, chemical and biological reactors, energy conversion systems, separation and filtration systems, and medical, pharmaceutical, and environmental monitoring. The success of LoC technology relies on the ability to manipulate ions and molecules in increasingly small volumes of fluid (nL and less). With decreasing critical length scales for devices made possible by advances in microfabrication and nanofabrication, the device surface-area-to volume ratio has made the role of surface properties critical to operation and novel functionality of many of these devices. Of the various surface properties, surface charge presents a unique parameter with broad applicability for engineering new device functionalities. Gated nanofluidic devices, geometrically analogous to semiconductor field-effect transistors, feature a nanofluidic channel with a “gate” electrode embedded in the nanochannel wall, providing an active, tunable region for manipulation of local surface charge. Specifically, an independently controlled potential applied to the embedded gate electrode allows systematic manipulation of the surface charge density at the dielectric-electrolyte interface. Fabrication protocols for gated nanofluidic devices with sub-20 nm critical length scales were developed that rely on UV lithography, wet etching, ii and oxygen plasma bonding techniques. Active control over ionic transport through the nanochannel was monitored by changes in current as a function of gate potential, electrolyte type, electrolyte concentration, and solution pH. The measured current was referenced with respect to the ungated or intrinsic case, or the case when only an axial potential was applied with no gate potential. In this dissertation, it was experimentally verified that the gate electrode additionally alters the electric field in the nanochannel by modifying the potential in the nanochannel near the gate electrode/dielectric/solution interface. In the surface charge governed transport regime, the gate electrode was used to switch off the measured current for a fixed axial potential, where repeatable on/off switching was demonstrated. Local variation of surface charge by the gate electrode on transport of multivalent aqueous electrolytes and electrolyte mixtures, which form the basis for biological or practical applications, was investigated as a function of cation type. In agreement with previous anomalous transport reports, no significant difference was observed for the intrinsic nanochannel conductance of KCl compared to NaCl. Conductance decreased for MgCl2 and CaCl2 at concentrations typically associated with surface charge governed transport for monovalent electrolytes, suggesting a decrease in the total surface charge due to divalent cation adsorption at the negatively charged walls. Data from KCl and 2+ CaCl2 electrolyte mixtures clearly indicated that Ca in the mixture is the dominating ion as determined by a decrease in surface charge density when CaCl2 was added and a surface charge density that was independent of KCl concentration for %CaCl2 > 25%. Cation adsorption to the charged walls regulates the surface charge density thus limiting iii the ability of the gate electrode to alter the net surface charge and consequently modulate nanochannel conductance as a function of cation type. iv Dedication This document is dedicated to Ciana Marie Pinti. v Acknowledgments I would like to thank my advisor, Shaurya Prakash, for his guidance and support throughout my PhD. I would like to thank Professor A.T. Conlisk for his insight and useful suggestions that have helped guide the work in this dissertation. I would also like to thank my committee members, Professor Carlos Castro and Professor Steven Ringel, for their useful insights into my work. I would like to thank the staff at Nanotech West laboratories for their assistance with equipment during fabrication and characterization of nanofluidic device. I want to thank all of my fellow lab mates for their hard work and the many things that I have learned from them over the years. Special thanks to Caitlin Boone, whose dedication and enthusiasm have made her a true pleasure to work with over the past year. I would also like to thank Kaushik Rangharajan for his work developing COMSOL models to describe ionic transport behavior in the nanofluidic device presented here. Past and current undergraduate researchers, Neil Ramirez, David Horner, Kyle Wellmerling, and Bowen Wang, who assisted with experimental setup and worked on projects related to this work, are acknowledged for their hard work, creativity, and insightful questions. I would also like to thank Professor Harvey Zambrano for useful conversations that gave me a fresh perspective at different stages of this project. Eugene Sosnov is acknowledged for providing me with initial training in clean room processes. Special thanks to Karen vi Bellman Lowe for helping me transition from Physics to Mechanical Engineering, for her unconditional support, and her invaluable friendship. Finally, I would like to thank my parents for their unconditional love and support and their reassurance throughout my academic career. Special thanks to Frederik Fuest for his encouragement and support. I would like to acknowledge partial financial support for this research from the US Army Research Office (ARO) through grant number W911NF09C0079 and the National Science Foundation through grant CBET-1335946. I would also like to thank the National Science Foundation for support through their Graduate Research Fellowship Program (GRFP) and the Ohio State University for their support through the Distinguished University Fellowship for my first year and dissertation year. vii Vita May 2006 .......................................................Charles F. Brush High School 2010................................................................B.S. Physics, John Carroll University 2014................................................................M.S. Mechanical Engineering, Ohio State University 2010 to present ..............................................Graduate Research Fellow, Department of Mechanical Engineering, The Ohio State University Publications 1. Marie Fuest, C. Boone, A.T. Conlisk, and S. Prakash; Cation Dependent Surface Charge Regulation in Gated Nanofluidic Devices. 2015, (submitted). 2. K. K. Rangharajan, Marie Fuest, A.T. Conlisk, S. Prakash; Transport of Multicomponent, Multivalent Electrolyte Solutions across Nanocapillaries. Microfluidics and Nanofluidics, 2015, (in review) 3. S. Prakash, H. A. Zambrano, Marie Fuest, C. Boone, E. Rosenthal-Kim, N. Vasquez, and A.T. Conlisk; Electrokinetic Transport in Silica Nanochannels viii with Asymmetric Surface Charge. Microfluidics and Nanofluidics, 2015, 19 (6), 1455-1464. 4. Marie Fuest, C. Boone, A.T. Conlisk, and S. Prakash; Cation Dependent Transport in a Field Effect Nanofluidic Device. Technical Digest of the 18th International Conference on Solid-State Sensors, Actuators and Microsystems Transducers 2015, Anchorage, Alaska, 6/21-25/2015 Transducers Research Foundation, Cleveland (2015). 5. Marie Fuest, C. Boone, K. K. Rangharajan, A.T. Conlisk, S. Prakash; A Three- State Nanofluidic Field Effect Switch. Nano letters, 2015, 15 (4), pp 2365–2371. 6. Marie Pinti (Fuest), H.A. Zambrano, K.K. Rangharajan, B. Wang, A.T. Conlisk, and S. Prakash; Active surface charge control for artificial ion pumps, Technical Digest of the Hilton Head Workshop 2014: A Solid-State Sensors, Actuators and Microsystems Workshop, Hilton Head, South Carolina, 6/8-12/2014 Transducers Research Foundation, Cleveland (2014), pp. 315-317. 7. Marie Pinti (Fuest), T. Kambham, B. Wang, S. Prakash; Fabrication of centimeter long, ultra-low aspect ratio nanochannel networks in borosilicate glass substrates. Journal of Nanotechnology in Engineering and Medicine, 2013, 4, pp. 021003 (1-7). 8. Marie Pinti (Fuest), S. Prakash. (2013). Fabrication of Hybrid Micro- Nanofluidic Devices with Centimeter Long Ultra-Low Aspect Ratio Nanochannels. 2013 Proceedings of the 2013 ASME International Mechanical Engineering Congress and Exposition, San Diego, California. ix 9. H A Zambrano, Marie Pinti (Fuest), A. T. Conlisk, S Prakash; Electrokinetic transport in a water–chloride nanofilm in contact with a silica surface with discontinuous charged patches. Microfluidics and Nanofluidics, 2012, 13(5), 735-747. 10. V. V. Swaminathan, L. R. Gibson II, Marie Pinti (Fuest), S. Prakash, P. W. Bohn, M.A. Shannon; Ionic transport in nanocapillary membrane systems. Journal of Nanoparticle Research, 2012, 14(8), 951-965. 11. S. Prakash, Marie Pinti (Fuest), K. Bellman; Variable cross-section nanopores fabricated in silicon nitride membranes using a transmission electron microscope. Journal of Micromechanics and Microengineering, 2012, 22 067002.
Load more

Recommended publications
  • Polyelectrolyte Assisted Charge Titration Spectrometry: Applications to Latex and Oxide Nanoparticles
    Polyelectrolyte assisted charge titration spectrometry: applications to latex and oxide nanoparticles F. Mousseau1*, L. Vitorazi1, L. Herrmann1, S. Mornet2 and J.-F. Berret1* 1Matière et Systèmes Complexes, UMR 7057 CNRS Université Denis Diderot Paris-VII, Bâtiment Condorcet, 10 rue Alice Domon et Léonie Duquet, 75205 Paris, France. 2Institut de Chimie de la Matière Condensée de Bordeaux, UPR CNRS 9048, Université Bordeaux 1, 87 Avenue du Docteur A. Schweitzer, Pessac cedex F-33608, France. Abstract: The electrostatic charge density of particles is of paramount importance for the control of the dispersion stability. Conventional methods use potentiometric, conductometric or turbidity titration but require large amount of samples. Here we report a simple and cost-effective method called polyelectrolyte assisted charge titration spectrometry or PACTS. The technique takes advantage of the propensity of oppositely charged polymers and particles to assemble upon mixing, leading to aggregation or phase separation. The mixed dispersions exhibit a maximum in light scattering as a function of the volumetric ratio �, and the peak position �!"# is linked to the particle charge density according to � ~ �!�!"# where �! is the particle diameter. The PACTS is successfully applied to organic latex, aluminum and silicon oxide particles of positive or negative charge using poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate). The protocol is also optimized with respect to important parameters such as pH and concentration, and to the polyelectrolyte molecular weight. The advantages of the PACTS technique are that it requires minute amounts of sample and that it is suitable to a broad variety of charged nano-objects. Keywords: charge density – nanoparticles - light scattering – polyelectrolyte complex Corresponding authors: [email protected] [email protected] To appear in Journal of Colloid and Interface Science leading to their condensation and to the formation of the electrical double layer [1].
    [Show full text]
  • Influence of Polyelectrolyte Multilayer Properties on Bacterial Adhesion
    polymers Article Influence of Polyelectrolyte Multilayer Properties on Bacterial Adhesion Capacity Davor Kovaˇcevi´c 1, Rok Pratnekar 2, Karmen GodiˇcTorkar 2, Jasmina Salopek 1, Goran Draži´c 3,4,5, Anže Abram 3,4,5 and Klemen Bohinc 2,* 1 Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb 10000, Croatia; [email protected] (D.K.); [email protected] (J.S.) 2 Faculty of Health Sciences, Ljubljana 1000, Slovenia; [email protected] (R.P.); [email protected] (K.G.T.) 3 Jožef Stefan Institute, Ljubljana 1000, Slovenia; [email protected] (G.D.); [email protected] (A.A.) 4 National Institute of Chemistry, Ljubljana 1000, Slovenia 5 Jožef Stefan International Postgraduate School, Ljubljana 1000, Slovenia * Correspondence: [email protected]; Tel.: +386-1300-1170 Academic Editor: Christine Wandrey Received: 16 August 2016; Accepted: 14 September 2016; Published: 26 September 2016 Abstract: Bacterial adhesion can be controlled by different material surface properties, such as surface charge, on which we concentrate in our study. We use a silica surface on which poly(allylamine hydrochloride)/sodium poly(4-styrenesulfonate) (PAH/PSS) polyelectrolyte multilayers were formed. The corresponding surface roughness and hydrophobicity were determined by atomic force microscopy and tensiometry. The surface charge was examined by the zeta potential measurements of silica particles covered with polyelectrolyte multilayers, whereby ionic strength and polyelectrolyte concentrations significantly influenced the build-up process. For adhesion experiments, we used the bacterium Pseudomonas aeruginosa. The extent of adhered bacteria on the surface was determined by scanning electron microscopy. The results showed that the extent of adhered bacteria mostly depends on the type of terminating polyelectrolyte layer, since relatively low differences in surface roughness and hydrophobicity were obtained.
    [Show full text]
  • UNIVERSITY of SOUTH CAROLINA EMCH 792C Micro/Nanofluidics And
    UNIVERSITY OF SOUTH CAROLINA EMCH 792C Micro/nanofluidics and Lab-on-a-Chip Fall 2009 OUTLINE Instructor Prof. Guiren Wang Room A221, 300 Main Street Office hours: Tu 6:00 – 7:00 p.m., Fr 6:00 – 7:00 p.m. Walk-ins are welcome at other times. Tel. 777-8013 (office), e-mail: [email protected] Textbook • Micro- and Nanoscale Fluid Mechanics for Engineers: Transport in Microfluidic Devices By Brian J. Kirby. 2009. References • Tabeling, P. Introduction to Microfluidics, Oxford, 2005. • Probstein, R.F. Physicochemical Hydrodynamics, 2nd Ed., Wiley, 1994 • Bruss, H. Theoretical Microfluidics, Oxford, 2008. • Nguyen, N-T and Wereley, S “Fundamentals and Applications of Microfluidics”, 2nd Edition, Artech House, ISBN: 1580539726 • Berthier J. and Silberzan, P. Microfluidics for Biotechnology. Artech House Publishers. ISBN: 1-58053-961-0. Catalog Course Description EMCH 792C Micro/nanofluidics and Lab-on-a-Chip. (3) Introduction of microlfuidics and applications in life science. Content: Fundamentals and engineering concept: Introduction of basic principle of fluid mechanics, Navier-Stokes equation, non-slip condition, capillary, drop and micro/nanoparticle, electrokinetics; Introduction to microfabrication: soft-lithography, self-assembled monolayers; Microfluidic components and sample preparation: micro- pump, filter, valve, dispenser, mixer, reactor, preconcentrator, separation based on electrokinetics, microactuator and particle manipulator; Experimental measurements: microscopy, fluorescence and laser-induced fluorescence, measurement of flow velocity, temperature and concentration; Applications in chemistry and life science: sensors for pressure, velocity, concentration, temperature, biosensor in environmental monitoring and biodefence, clinical diagnostics, drug discovery and delivery, etc. Course Objectives: At the conclusion of this course, students will be able to: 1. Understanding some advanced fluid mechanics relevant to micro scale device.
    [Show full text]
  • Surface Polarization Effects in Confined Polyelectrolyte Solutions
    Surface polarization effects in confined polyelectrolyte solutions Debarshee Bagchia , Trung Dac Nguyenb , and Monica Olvera de la Cruza,b,c,1 aDepartment of Materials Science and Engineering, Northwestern University, Evanston, IL 60208; bDepartment of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208; and cDepartment of Physics and Astronomy, Northwestern University, Evanston, IL 60208 Contributed by Monica Olvera de la Cruz, June 24, 2020 (sent for review April 21, 2020; reviewed by Rene Messina and Jian Qin) Understanding nanoscale interactions at the interface between ary conditions (18, 19). However, for many biological settings two media with different dielectric constants is crucial for con- as well as in supercapacitor applications, molecular electrolytes trolling many environmental and biological processes, and for confined by dielectric materials, such as graphene, are of interest. improving the efficiency of energy storage devices. In this Recent studies on dielectric confinement of polyelectrolyte by a contributed paper, we show that polarization effects due to spherical cavity showed that dielectric mismatch leads to unex- such dielectric mismatch remarkably influence the double-layer pected symmetry-breaking conformations, as the surface charge structure of a polyelectrolyte solution confined between two density increases (20). The focus of the present study is the col- charged surfaces. Surprisingly, the electrostatic potential across lective effects of spatial confinement by two parallel surfaces
    [Show full text]
  • Semester II, 2015-16 Department of Physics, IIT Kanpur PHY103A: Lecture # 5 Anand Kumar
    Semester II, 2017-18 Department of Physics, IIT Kanpur PHY103A: Lecture # 8 (Text Book: Intro to Electrodynamics by Griffiths, 3rd Ed.) Anand Kumar Jha 19-Jan-2018 Summary of Lecture # 7: • Electrostatic Boundary Conditions E E = Electric Field: = above below E − E = 00 above− below � 0 above − below Electric Potential: V V = 0 above − below • Basic Properties of Conductors (1) The electric field = 0 inside a conductor, always. = 0 = = 0 (2) The charge density inside a conductor. This is because . (3) Any net charge resides on the surface. Why? To minimize the energy. 0 ⋅ (4) A conductor is an equipotential. (5) is perpendicular to the surface, just outside the conductor. 2 Summary of Lecture # 7: Prob. 2.36 (Griffiths, 3rd Ed. ): - Surface charge ? = = − 2 - Surface charge ? 4 + - Surface charge ? = − 2 4 1 2 - ( ) ? = 4 out 2 1 0 � - ( ) ? = 4 out 2 10 �+ - ( ) ? =4 out out 2 � - Force on ? 0 40 - Force on ? 0 3 Summary of Lecture # 7: Prob. 2.36 (Griffiths, 3rd Ed. ): - Surface charge ? = Same ª = − 2 Same - Surface charge ? 4 ª + - Surface charge ? = − 2 Changes � 4 1 2 = - ( ) ? 4 Same ª out 2 1 0 � = 4 - ( ) ? Same ª out 2 � 10 + Changes � - ( ) ? =4 out out 2 - Force on ? 0 0 � 4 Same ª Bring in a third - Force on ? 0 Same ª charge 4 Surface Charge and the Force on a Conductor: What is the electrostatic force on the patch? Force per unit area on the patch is: = (? ) = other = + , above other patch above = + 2 other 0 � = + , below other patch below 1 = = + 2 2 other − � other above below 0 But, inside a metal, = , so = 0 below = = + = 2 2 other � above other � � 5 0 0 0 Surface Charge and the Force on a Conductor: What is the electrostatic force on the patch? Force per unit area on the patch is: = (? ) = other = = 2 other � above � Force per unit0 area on the patch is: 0 = = 2 2 other � Force per unit area is pressure.0 So, the electrostatic pressure is: = = 2 2 20 2 6 0 Capacitor: Two conductors with charge and .
    [Show full text]
  • Ion Current Rectification in Extra-Long Nanofunnels
    applied sciences Article Ion Current Rectification in Extra-Long Nanofunnels Diego Repetto, Elena Angeli * , Denise Pezzuoli, Patrizia Guida, Giuseppe Firpo and Luca Repetto Department of Physics, University of Genoa, via Dodecaneso 33, 16146 Genoa, Italy; [email protected] (D.R.); [email protected] (D.P.); [email protected] (P.G.); giuseppe.fi[email protected] (G.F.); [email protected] (L.R.) * Correspondence: [email protected] Received: 29 April 2020; Accepted: 25 May 2020; Published: 28 May 2020 Abstract: Nanofluidic systems offer new functionalities for the development of high sensitivity biosensors, but many of the interesting electrokinetic phenomena taking place inside or in the proximity of nanostructures are still not fully characterized. Here, to better understand the accumulation phenomena observed in fluidic systems with asymmetric nanostructures, we study the distribution of the ion concentration inside a long (more than 90 µm) micrometric funnel terminating with a nanochannel. We show numerical simulations, based on the finite element method, and analyze how the ion distribution changes depending on the average concentration of the working solutions. We also report on the effect of surface charge on the ion distribution inside a long funnel and analyze how the phenomena of ion current rectification depend on the applied voltage and on the working solution concentration. Our results can be used in the design and implementation of high-performance concentrators, which, if combined with high sensitivity detectors, could drive the development of a new class of miniaturized biosensors characterized by an improved sensitivity. Keywords: nanofunnel; FEM simulation; ionic current rectification; micro-nano structure interface 1.
    [Show full text]
  • Beryllium Desorption from Minerals and Organic Ligands Over Time
    Chemical Geology 439 (2016) 52–58 Contents lists available at ScienceDirect Chemical Geology journal homepage: www.elsevier.com/locate/chemgeo Beryllium desorption from minerals and organic ligands over time Vanessa Boschi ⁎,JaneK.Willenbring Department of Earth and Environmental Science, University of Pennsylvania, 251 Hayden Hall, 240 South 33rd Street, Philadelphia, PA 19104, USA article info abstract Article history: Beryllium isotopes sorbed to sediments have provided useful tools in the field of geochronology and geomor- Received 13 April 2016 phology over the last few decades. The use of beryllium isotopes relies on the premise that beryllium sorbed to Received in revised form 3 June 2016 sediments is unaltered over large timescales. Changes in the environmental chemistry, either in-situ or en Accepted 10 June 2016 route from soil to fluvial system, to the ocean, can cause beryllium desorption and may preclude some beryllium Available online 11 June 2016 isotopic applications. Keywords: Four mechanisms were tested to determine the relative desorption potential of beryllium including a reduction Beryllium in pH, an increase in ionic strength (NaCl) and complexation by soluble organic (malonic acid) and inorganic spe- Desorption cies (NaF). To assess the relative effect of each mechanism on beryllium desorption from both organic and min- Minerals eral fractions, we prepared separate solutions of beryllium bound to minerals and organic compounds and Organic ligands measured beryllium concentrations in solution before and after each chemical perturbation. We conclude a re- Inner and outer sphere complexation duction in pH resulted in the greatest amount of desorption among the four treatments, removing 97% and 75% of sorbed beryllium from illite and montmorillonite, respectively, and none from the organic ligands tested.
    [Show full text]
  • 6.007 Lecture 5: Electrostatics (Gauss's Law and Boundary
    Electrostatics (Free Space With Charges & Conductors) Reading - Shen and Kong – Ch. 9 Outline Maxwell’s Equations (In Free Space) Gauss’ Law & Faraday’s Law Applications of Gauss’ Law Electrostatic Boundary Conditions Electrostatic Energy Storage 1 Maxwell’s Equations (in Free Space with Electric Charges present) DIFFERENTIAL FORM INTEGRAL FORM E-Gauss: Faraday: H-Gauss: Ampere: Static arise when , and Maxwell’s Equations split into decoupled electrostatic and magnetostatic eqns. Electro-quasistatic and magneto-quasitatic systems arise when one (but not both) time derivative becomes important. Note that the Differential and Integral forms of Maxwell’s Equations are related through ’ ’ Stoke s Theorem and2 Gauss Theorem Charges and Currents Charge conservation and KCL for ideal nodes There can be a nonzero charge density in the absence of a current density . There can be a nonzero current density in the absence of a charge density . 3 Gauss’ Law Flux of through closed surface S = net charge inside V 4 Point Charge Example Apply Gauss’ Law in integral form making use of symmetry to find • Assume that the image charge is uniformly distributed at . Why is this important ? • Symmetry 5 Gauss’ Law Tells Us … … the electric charge can reside only on the surface of the conductor. [If charge was present inside a conductor, we can draw a Gaussian surface around that charge and the electric field in vicinity of that charge would be non-zero ! A non-zero field implies current flow through the conductor, which will transport the charge to the surface.] … there is no charge at all on the inner surface of a hollow conductor.
    [Show full text]
  • University of Florida Thesis Or Dissertation Formatting
    THE RAREFIED GAS ELECTRO JET (RGEJ) MICRO-THRUSTER FOR PROPULSION OF SMALL SATELLITES By ARIEL BLANCO A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2017 © 2017 Ariel Blanco To my family, friends, and mentors ACKNOWLEDGMENTS I thank my parents and maternal grandmother for their continuous support and encouragement, for teaching me to persevere and value the pursuit of knowledge. I am extremely thankful to my friends and lab colleagues who have helped me so much, not only academically but also by giving me moral support and solidarity. Finally, yet importantly, it is a genuine pleasure to express my deep sense of thanks and gratitude to all my mentors, especially my advisor, Dr. Subrata Roy. Without his guidance, mentoring, and support, this study would not have been completed. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 8 LIST OF FIGURES ........................................................................................................ 10 ABSTRACT ................................................................................................................... 12 CHAPTER 1 INTRODUCTION ...................................................................................................
    [Show full text]
  • Chapter 5 Capacitance and Dielectrics
    Chapter 5 Capacitance and Dielectrics 5.1 Introduction...........................................................................................................5-3 5.2 Calculation of Capacitance ...................................................................................5-4 Example 5.1: Parallel-Plate Capacitor ....................................................................5-4 Interactive Simulation 5.1: Parallel-Plate Capacitor ...........................................5-6 Example 5.2: Cylindrical Capacitor........................................................................5-6 Example 5.3: Spherical Capacitor...........................................................................5-8 5.3 Capacitors in Electric Circuits ..............................................................................5-9 5.3.1 Parallel Connection......................................................................................5-10 5.3.2 Series Connection ........................................................................................5-11 Example 5.4: Equivalent Capacitance ..................................................................5-12 5.4 Storing Energy in a Capacitor.............................................................................5-13 5.4.1 Energy Density of the Electric Field............................................................5-14 Interactive Simulation 5.2: Charge Placed between Capacitor Plates..............5-14 Example 5.5: Electric Energy Density of Dry Air................................................5-15
    [Show full text]
  • Electrical Double Layer Interactions with Surface Charge Heterogeneities
    Electrical double layer interactions with surface charge heterogeneities by Christian Pick A dissertation submitted to Johns Hopkins University in conformity with the requirements for the degree of Doctor of Philosophy Baltimore, Maryland October 2015 © 2015 Christian Pick All rights reserved Abstract Particle deposition at solid-liquid interfaces is a critical process in a diverse number of technological systems. The surface forces governing particle deposition are typically treated within the framework of the well-known DLVO (Derjaguin-Landau- Verwey-Overbeek) theory. DLVO theory assumes of a uniform surface charge density but real surfaces often contain chemical heterogeneities that can introduce variations in surface charge density. While numerous studies have revealed a great deal on the role of charge heterogeneities in particle deposition, direct force measurement of heterogeneously charged surfaces has remained a largely unexplored area of research. Force measurements would allow for systematic investigation into the effects of charge heterogeneities on surface forces. A significant challenge with employing force measurements of heterogeneously charged surfaces is the size of the interaction area, referred to in literature as the electrostatic zone of influence. For microparticles, the size of the zone of influence is, at most, a few hundred nanometers across. Creating a surface with well-defined patterned heterogeneities within this area is out of reach of most conventional photolithographic techniques. Here, we present a means of simultaneously scaling up the electrostatic zone of influence and performing direct force measurements with micropatterned heterogeneously charged surfaces by employing the surface forces apparatus (SFA). A technique is developed here based on the vapor deposition of an aminosilane (3- aminopropyltriethoxysilane, APTES) through elastomeric membranes to create surfaces for force measurement experiments.
    [Show full text]
  • Graduate Program in Materials Science and Engineering
    Interdisciplinary Faculty of Materials Science and Engineering Graduate Program in Materials Science and Engineering Materials Science and Engineering Graduate Program Self Study January 2012 1 Table of Contents List of Figures ................................................................................................................................................ 5 List of Tables ................................................................................................................................................. 6 1. INTRODUCTION ....................................................................................................................................... 7 1.1. Welcome ............................................................................................................................................ 7 1.2. Charge to the Review Team .............................................................................................................. 8 1.3. Itinerary and Contact Persons ........................................................................................................... 9 2. TEXAS A&M UNIVERSITY ..................................................................................................................... 11 2.1. The University System ..................................................................................................................... 11 2.2. Texas A&M University .....................................................................................................................
    [Show full text]