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Niu Y, Ma Y, Xie Y. Soft Memristor at a Microbubble Interface. NANO LETTERS 2024; 24:10475-10481. [PMID: 39116301 DOI: 10.1021/acs.nanolett.4c02136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
Memristors show promising features for neuromorphic computing. Here we report a soft memristor based on the liquid-vapor surface of a microbubble. The thickness of the liquid film was modulated by electrostatic and interfacial forces, enabling resistance switches. We found a pinched current hysteresis at scanning periods between 1.6 and 51.2 s, while representing a resistor below 1.6 s and a diode-like behavior above 51.2 s. We approximate the thickening/thinning dynamics of liquid film by pressure-driven flow at the interface and derived the impacts of salt concentration and voltage amplitude on the memory effects. Our work opens a new approach to building nanofluidic memristors by a soft interface, which may be useful for new types of neuromorphic computing in the future.
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Affiliation(s)
- Yueke Niu
- School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Yu Ma
- School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Yanbo Xie
- National Key Laboratory of Aircraft Configuration Design, School of Aeronautics and Institute of Extreme Mechanics, Northwestern Polytechnical University, Xi'an, 710072, China
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2
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Fauvel M, Trybala A, Tseluiko D, Starov VM, Bandulasena HCH. Foam-Based Electrophoretic Separation of Charged Dyes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:13935-13942. [PMID: 36322953 PMCID: PMC9671044 DOI: 10.1021/acs.langmuir.2c02228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/25/2022] [Indexed: 06/16/2023]
Abstract
Electrophoretic separation of a fluorescent dye mixture, containing rhodamine B (RB) and fluorescein, in liquid foams stabilized by anionic, cationic, or non-ionic surfactants in water-glycerol mixtures was studied in a custom-designed foam separation device. The effects of the external electric field applied across the foam and the initial pH of the solution on the effectiveness of separation were also studied. The fluid motion due to electroosmosis and the resulting back pressure within the foam and local pH changes were found to be complex and affected the separation. Fluorescein dye molecules, which have a positive or negative charge depending on the solution pH, aggregated in the vicinity of an electrode, leaving a pure band of neutral dye RB. The effectiveness of the separation was quantified by the percentage width of the pure RB band, which was found to be between 29 and 42%. This study demonstrates the potential of liquid foam as a platform for electrophoretic separation.
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Affiliation(s)
- Matthieu Fauvel
- Department
of Chemical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, U.K.
| | - Anna Trybala
- Department
of Chemical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, U.K.
| | - Dmitri Tseluiko
- Department
of Mathematics, Loughborough University, Loughborough, Leicestershire LE11 3TU, U.K.
| | - Victor Mikhilovich Starov
- Department
of Chemical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, U.K.
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3
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Fauvel M, Trybala A, Tseluiko D, Starov VM, Bandulasena HCH. Stability of Two-Dimensional Liquid Foams under Externally Applied Electric Fields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6305-6321. [PMID: 35546544 PMCID: PMC9134501 DOI: 10.1021/acs.langmuir.2c00026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/26/2022] [Indexed: 06/15/2023]
Abstract
Liquid foams are highly complex systems consisting of gas bubbles trapped within a solution of surfactant. Electroosmotic effects may be employed to induce fluid flows within the foam structure and impact its stability. The impact of external electric fields on the stability of a horizontally oriented monolayer of foam (2D foam) composed of anionic, cationic, non-ionic, and zwitterionic surfactants was investigated, probing the effects of changing the gas-liquid and solid-liquid interfaces. Time-lapse recordings were analyzed to investigate the evolution of foam over time subject to varying electric field strengths. Numerical simulations of electroosmotic flow of the same system were performed using the finite element method. Foam stability was affected by the presence of an external electric field in all cases and depended on the surfactant type, strength of the electric field, and the solid material used to construct the foam cell. For the myristyltrimethylammonium bromide (MTAB) foam in a glass cell, the time to collapse 50% of the foam was increased from ∼25 min under no electric field to ∼85 min under an electric field strength of 2000 V/m. In comparison, all other surfactants trialed exhibited faster foam collapse under external electric fields. Numerical simulations provided insight as to how different zeta potentials at the gas-liquid and solid-liquid interfaces affect fluid flow in different elements of the foam structure under external electric fields, leading to a more stable or unstable foam.
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Affiliation(s)
- Matthieu Fauvel
- Department
of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
| | - Anna Trybala
- Department
of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
| | - Dmitri Tseluiko
- Department
of Mathematics, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
| | - Victor Mikhilovich Starov
- Department
of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
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Fu L, Ybert C, Bonhomme O, Joly L, Biance AL. Electrokinetic sweeping of colloids at a reactive magnesium oxide interface. SOFT MATTER 2021; 17:8705-8711. [PMID: 34523665 DOI: 10.1039/d1sm00908g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Investigating the electrokinetic (EK) response in the vicinity of interfaces has regained interest due to the development of new membrane based processes for energy harvesting or soil depollution. However, the case of reactive interfaces, ubiquitous in these processes, remains scarcely explored. Here we experimentally investigate the EK response of a model interface between an aqueous electrolyte and a bulk MgO crystal surface (100), for different pH. For that purpose, we use a lab-scale non invasive method to monitor the zeta potential of the interface versus time, by confocal fluorescent particle tracking. An unexpected motion of the particles, repelled and then attracted again by the interface is observed. We attributed this motion to the surface reactivity, inducing ion concentration gradients perpendicular to the interface and subsequent diffusiophoresis of the charged particle. Accordingly, we could describe at a semi-quantitative level the particle dynamics by solving numerically the Poisson-Nernst-Planck equations to establish concentration profile in the system and subsequent diffusiophoretic motion. These experiments open the way to the characterization of both the EK response and the reaction rate in the vicinity of reactive interfaces.
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Affiliation(s)
- Li Fu
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, 6 Villeurbanne, France.
| | - Christophe Ybert
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, 6 Villeurbanne, France.
| | - Oriane Bonhomme
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, 6 Villeurbanne, France.
| | - Laurent Joly
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, 6 Villeurbanne, France.
- Institut Universitaire de France (IUF), 1 rue Descartes, 75005 Paris, France
| | - Anne-Laure Biance
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, 6 Villeurbanne, France.
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Uematsu Y, Bonthuis DJ, Netz RR. Nanomolar Surface-Active Charged Impurities Account for the Zeta Potential of Hydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:3645-3658. [PMID: 32167772 DOI: 10.1021/acs.langmuir.9b03795] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The electrification of hydrophobic surfaces is an intensely debated subject in physical chemistry. We theoretically study the ζ potential of hydrophobic surfaces for varying pH and salt concentration by solving the Poisson-Boltzmann and Stokes equations with individual ionic adsorption affinities. Using the ionic surface affinities extracted from the experimentally measured surface tension of the air-electrolyte interface, we first show that the interfacial adsorption and repulsion of small inorganic ions such as H3O+, OH-, HCO3-, and CO32- cannot account for the ζ potential observed in experiments because the surface affinities of these ions are too small. Even if we take hydrodynamic slip into account, the characteristic dependence of the ζ potential on pH and salt concentration cannot be reproduced. Instead, to explain the sizable experimentally measured ζ potential of hydrophobic surfaces, we assume minute amounts of impurities in the water and include the impurities' acidic and basic reactions with water. We find good agreement between our predictions and the reported experimental ζ potential data of various hydrophobic surfaces if we account for impurities that consist of a mixture of weak acids (pKa = 5-7) and weak bases (pKb = 12) at a concentration of the order of 10-7 M.
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Affiliation(s)
- Yuki Uematsu
- Department of Physics, Kyushu University, 819-0395 Fukuoka, Japan
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France
| | - Douwe Jan Bonthuis
- Institute of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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Hussein Sheik A, Montazersadgh F, Starov VM, Trybala A, Wijayantha KGU, Bandulasena HCH. Electrokinetic Transport of a Charged Dye in a Freely Suspended Liquid Film: Experiments and Numerical Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1183-1191. [PMID: 31957457 DOI: 10.1021/acs.langmuir.9b03852] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electrokinetic transport of a charged dye within a free liquid film stabilized by a cationic surfactant, trimethyl(tetradecyl)ammonium bromide, subjected to an external electric field was investigated. Confocal laser scanning microscopy was used to visualize fluorescein isothiocyanate (FITC) separation within the stabilized liquid film. Numerical simulations were performed using the finite element method to model the dynamics of charged dye separation fronts observed in the experiments. Because of the electrochemical reactions at the electrodes, significant spatial and temporal pH changes were observed within the liquid film. These local pH changes could affect the local zeta potential at the gas-liquid and solid-liquid film boundaries; hence, the flow field was found to be highly dynamic and complex. The charged dye (FITC) used in the experiments is pH-sensitive, and therefore, electrophoresis of the dye also depended on the local pH. The pH and the electroosmotic flow field predicted from the numerical simulations were useful for understanding charged dye separation near both the anode and the cathode.
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Affiliation(s)
| | - Faraz Montazersadgh
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering , Loughborough University , Loughborough LE11 3TU , U.K
| | | | - Anna Trybala
- Department of Chemical Engineering , Loughborough University , Loughborough LE11 3TU , U.K
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Fu L, Joly L, Merabia S. Giant Thermoelectric Response of Nanofluidic Systems Driven by Water Excess Enthalpy. PHYSICAL REVIEW LETTERS 2019; 123:138001. [PMID: 31697539 DOI: 10.1103/physrevlett.123.138001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 07/11/2019] [Indexed: 06/10/2023]
Abstract
Nanofluidic systems could in principle be used to produce electricity from waste heat, but current theoretical descriptions predict a rather poor performance as compared to thermoelectric solid materials. Here we investigate the thermoelectric response of NaCl and NaI solutions confined between charged walls, using molecular dynamics simulations. We compute a giant thermoelectric response, 2 orders of magnitude larger than the predictions of standard models. We show that water excess enthalpy-neglected in the standard picture-plays a dominant role in combination with the electro-osmotic mobility of the liquid-solid interface. Accordingly, the thermoelectric response can be boosted using surfaces with large hydrodynamic slip. Overall, the heat harvesting performance of the model systems considered here is comparable to that of the best thermoelectric materials, and the fundamental insight provided by molecular dynamics suggests guidelines to further optimize the performance, opening the way to recycle waste heat using nanofluidic devices.
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Affiliation(s)
- Li Fu
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Laurent Joly
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Samy Merabia
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
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Hartkamp R, Biance AL, Fu L, Dufrêche JF, Bonhomme O, Joly L. Measuring surface charge: Why experimental characterization and molecular modeling should be coupled. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Nguyen T, Phan CM. Influence of Hydrophilicity on the Thermal-Driven Surfactant Flow at the Air/Water Surface. ACS OMEGA 2018; 3:9060-9065. [PMID: 31459040 PMCID: PMC6645394 DOI: 10.1021/acsomega.8b00733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/31/2018] [Indexed: 06/10/2023]
Abstract
A series of Triton surfactants with increasing number of ethylene oxide (EO) groups were applied to investigate thermal-driven surface flow. It was found that the thermal gradient is proportional to the number of EO groups on the surface. This correlation leads to the linear correlation between the surfactant structure and the driving force of the surface flow. The friction force, in contrast, follows a monotonic but nonlinear correlation with surfactant's EO groups. The results demonstrate the possibilities to manipulate the surface flow, with potential applications in multiple-phase systems.
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Schnurbus M, Stricker L, Ravoo BJ, Braunschweig B. Smart Air-Water Interfaces with Arylazopyrazole Surfactants and Their Role in Photoresponsive Aqueous Foam. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6028-6035. [PMID: 29718669 PMCID: PMC5981290 DOI: 10.1021/acs.langmuir.8b00587] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/05/2018] [Indexed: 06/02/2023]
Abstract
A new light-switchable azo-surfactant arylazopyrazole tetraethylene glycol carboxylic acid (AAP-E4) was used as a molecular building block to functionalize macroscopic foams. AAP-E4 was studied in the bulk solution with UV/vis spectroscopy and at the interface with sum-frequency generation (SFG) as well as tensiometry. Additional foaming experiments were performed with a dynamic foam analyzer to study the role of AAP-E4 surfactants at the ubiquitous air-water interface as well as within macroscopic foam. In the bulk, it is possible to switch the AAP-E4 surfactant reversibly from trans to cis configurations and vice versa using 380 nm UV and 520 nm green light, respectively. At the interface, we demonstrate the excellent switching ability of AAP-E4 surfactants and a substantial modification of the surface tension. In addition, we show that the response of the interface is strongly influenced by lateral electrostatic interactions, which can be tuned by the charging state of AAP-E4. Consequently, the electrostatic disjoining pressure and thus the foam stability are highly dependent on the bulk pH and the charging state of the interface. For that reason, we have studied both the surface net charge (SFG) and the surface excess (tensiometry) as important parameters that determine foam stability in this system and show that neutral pH conditions lead to the optimal compromise between switching ability, surface excess, and surface charging. Measurements on the foam stability demonstrated that foams under irradiation with green light are more stable than foams irradiated with UV light.
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Affiliation(s)
- Marco Schnurbus
- Institute
of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Lucas Stricker
- Organic
Chemistry Institute and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany
| | - Bart Jan Ravoo
- Organic
Chemistry Institute and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany
| | - Björn Braunschweig
- Institute
of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
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