1
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Fraxedas J, Reguera D, Esplandiu MJ. Collective motion of Nafion-based micromotors in water. Faraday Discuss 2024; 249:424-439. [PMID: 37779462 DOI: 10.1039/d3fd00098b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Ion exchange is one of the most interesting processes occurring at the interface between aqueous solutions and polymers, such as the well-known Nafion. If the exchanged ions have different diffusion coefficients, this interchange generates local electric fields which can be harnessed to drive fluid motion. In this work, we show how it is possible to design and fabricate self-propelling microswimmers based on Nafion, driven by ion-exchange, and fueled by innocuous salts. These Nafion micromotors are made using colloidal lithography by micro/nanostructuring Nafion in the form of asymmetric rods. These microswimmers exhibit fascinating collective motion in water driven by the interplay of their self-generated chemical/electric fields and their capability to pump matter nearby towards the collective motile structure. The pumping activity of the microswimmers induces the formation of growing mobile clusters, whose velocity increases with size. Such dynamic structures are able to trap nearby micro/nano-objects while purifying the liquid, which acts both as the transport media and as fuel. Such phenomenology opens the door to potential applications in water remediation that are currently under development.
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Affiliation(s)
- Jordi Fraxedas
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain.
| | - David Reguera
- Departament de Física de la Matèria Condensada and Institute of Complex Systems (UBICS), Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
| | - María José Esplandiu
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain.
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2
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From radial to unidirectional water pumping in zeta-potential modulated Nafion nanostructures. Nat Commun 2022; 13:2812. [PMID: 35589767 PMCID: PMC9120507 DOI: 10.1038/s41467-022-30554-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 04/25/2022] [Indexed: 11/08/2022] Open
Abstract
Chemically propelled micropumps are promising wireless systems to autonomously drive fluid flows for many applications. However, many of these systems are activated by nocuous chemical fuels, cannot operate at high salt concentrations, or have difficulty for controlling flow directionality. In this work we report on a self-driven polymer micropump fueled by salt which can trigger both radial and unidirectional fluid flows. The micropump is based on the cation-exchanger Nafion, which produces chemical gradients and local electric fields capable to trigger interfacial electroosmotic flows. Unidirectional pumping is predicted by simulations and achieved experimentally by nanostructuring Nafion into microarrays with a fine tune modulation of surrounding surface zeta potentials. Nafion micropumps work in a wide range of salt concentrations, are reusable, and can be fueled by different salt cations. We demonstrate that they work with the common water-contaminant cadmium, using the own capture of this ion as fuel to drive fluid pumping. Thus, this system has potential for efficient and fast water purification strategies for environmental remediation. Unidirectional Nafion pumps also hold promise for effective analyte delivery or preconcentration for (bio)sensing assays. Chemically propelled micropumps are wireless fluid flow driving systems with many potential applications. Here, the authors report a self-driven reusable Nafion micropump fueled by different salt cations in a wide range of concentrations that triggers both radial and unidirectional flows, showing efficient water remediation capabilities.
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3
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Ashaju A, Wood JA, Lammertink RGH. Electrocatalytic Reaction Induced Colloidal Accumulation: The Role of Dielectrophoresis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3040-3050. [PMID: 35230108 PMCID: PMC8928468 DOI: 10.1021/acs.langmuir.1c01938] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 02/15/2022] [Indexed: 06/14/2023]
Abstract
A surface-driven flow is generated during the electrocatalytic reaction of a platinum-gold bielectrode within hydrogen peroxide. This flow can be experimentally visualized and quantified using micrometer-sized particles that are transported by a flow field. Tracer particles, which possess an inherent surface charge, also interact with the induced electric field and exhibit a collective behavior at the surface of the electrodes where they accumulate. The underlying mechanism for the accumulation dynamics demonstrated by these catalytic pump systems has so far been lacking. In this work, the accumulation dynamics and kinetics were experimentally investigated. With use of numerical simulations, we demonstrate that the self-driven particle accumulation is controlled by a positive dielectrophoretic force, mediated by the reaction-induced electric and flow field. These results contribute to the fundamental knowledge on immobilized bimetallic systems.
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4
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Ashaju A, Otten V, Wood JA, Lammertink RGH. Electrocatalytic Reaction Driven Flow: Role of pH in Flow Reversal. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:24876-24886. [PMID: 34824659 PMCID: PMC8607504 DOI: 10.1021/acs.jpcc.1c06458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 10/13/2021] [Indexed: 05/20/2023]
Abstract
Immobilized bimetallic structures generate fluid flow during electrocatalytic reactions with hydrogen peroxide, which is typically driven from the anodic metal to the cathodic metal similar to an electroosmotic flow. However, under low reactive regimes, the generated flow becomes fully reversed, which cannot be explained by the classical electroosmotic theory. This work aims at unraveling the origin and dynamics of this flow hysteresis through a combined experimental and numerical approach. The key electrocatalytic parameters that contribute to flow reversal are analyzed experimentally and numerically under low reactive regimes induced by bulk pH variations. The proton gradient that initiates chemomechanical actuation is probed with the use of fluorescence lifetime imaging. The fluid flow dynamics under reactive regimes are visualized by the use of particle tracking. Our numerical simulations elucidate the role of pH variations and additional ionic species (counterions) toward flow reversal. The combination of these techniques highlights the interplay between electrocatalytic and electrokinetic phenomena on the occurrence of flow reversal.
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Affiliation(s)
- Abimbola
A. Ashaju
- Soft Matter, Fluidics and Interfaces,
MESA+ Institute for Nanotechnology, University
of Twente, 7522NB Enschede, The Netherlands
| | - Veerle Otten
- Soft Matter, Fluidics and Interfaces,
MESA+ Institute for Nanotechnology, University
of Twente, 7522NB Enschede, The Netherlands
| | - Jeffery A. Wood
- Soft Matter, Fluidics and Interfaces,
MESA+ Institute for Nanotechnology, University
of Twente, 7522NB Enschede, The Netherlands
| | - Rob G. H. Lammertink
- Soft Matter, Fluidics and Interfaces,
MESA+ Institute for Nanotechnology, University
of Twente, 7522NB Enschede, The Netherlands
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5
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Plasmon‐Enhanced, Self‐Traced Nanomotors on the Surface of Silicon. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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6
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Yang J, Zheng J, Ai R, Lai Y, Chow TH, Shao L, Wang J. Plasmon-Enhanced, Self-Traced Nanomotors on the Surface of Silicon. Angew Chem Int Ed Engl 2021; 60:24958-24967. [PMID: 34535946 DOI: 10.1002/anie.202108487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/29/2021] [Indexed: 11/09/2022]
Abstract
Light-driven nanomotors have attracted much attention due to their potential applications. The movement of conventional nanomotors typically occurs in the solution phase, which limits their application fields. Utilizing visible light to drive nanomotors at the solid-liquid interface represents a grand challenge due to the large friction force between the nanomotor and the solid surface. Based on the attractive plasmon resonance of Au nanocrystals, for the first time, plasmon-enhanced Au nanocrystal-based nanomotors moving at the silicon-aqueous solution interface have been developed. Such nanomotors move with a clear trace engraved on the Si surface, representing an excellent and exceptional self-traced nanomotor system. In addition, the nanomotor trace on the Si surface also provides a unique and promising approach to the fabrication of nanoscale Si patterns, which is central to many applications, including microelectronics, sensing, information storage, and optoelectronics.
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Affiliation(s)
- Jianhua Yang
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Jiapeng Zheng
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Ruoqi Ai
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Yunhe Lai
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Tsz Him Chow
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Lei Shao
- Beijing Computational Science Research Center, Beijing, 100193, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China
| | - Jianfang Wang
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China
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7
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Möller N, Liebchen B, Palberg T. Shaping the gradients driving phoretic micro-swimmers: influence of swimming speed, budget of carbonic acid and environment. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:41. [PMID: 33759011 PMCID: PMC7987694 DOI: 10.1140/epje/s10189-021-00026-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/22/2021] [Indexed: 05/07/2023]
Abstract
pH gradient-driven modular micro-swimmers are investigated as a model for a large variety of quasi-two-dimensional chemi-phoretic self-propelled entities. Using three-channel micro-photometry, we obtain a precise large field mapping of pH at a spatial resolution of a few microns and a pH resolution of [Formula: see text] units for swimmers of different velocities propelling on two differently charged substrates. We model our results in terms of solutions of the three-dimensional advection-diffusion equation for a 1:1 electrolyte, i.e. carbonic acid, which is produced by ion exchange and consumed by equilibration with dissolved [Formula: see text]. We demonstrate the dependence of gradient shape and steepness on swimmer speed, diffusivity of chemicals, as well as the fuel budget. Moreover, we experimentally observe a subtle, but significant feedback of the swimmer's immediate environment in terms of a substrate charge-mediated solvent convection. We discuss our findings in view of different recent results from other micro-fluidic or active matter investigations. We anticipate that they are relevant for quantitative modelling and targeted applications of diffusio-phoretic flows in general and artificial micro-swimmers in particular.
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Affiliation(s)
- Nadir Möller
- Institute of Condensed Matter Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany.
- Max Planck Graduade Center, Institute of Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany.
| | - Benno Liebchen
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Thomas Palberg
- Institute of Condensed Matter Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany
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8
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Sun Y, Jiang J, Zhang G, Yuan N, Zhang H, Song B, Dong B. Visible Light-Driven Micromotor with Incident-Angle-Controlled Motion and Dynamic Collective Behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:180-187. [PMID: 33390019 DOI: 10.1021/acs.langmuir.0c02714] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Light-driven micromotor has become one of the research focuses in the past decade, and its motion behavior is usually controlled by light intensity, polarization, and light wavelength. Herein, the light incident angle is utilized to control the motion behavior of silica/Au/pentacene (SiO2/Au/PEN) spherical Janus micromotor. Under tilted irradiation, a single micromotor shows positive phototactic moving behavior without the addition of external chemical fuels, which relies on the photocatalytic reactions and the self-electrophoresis mechanism. Interestingly, when the incident light is tuned to the vertical angle, the SiO2/Au/PEN micromotor stops moving. Similarly, a number of SiO2/Au/PEN micromotors exhibit the same "on-off" motion change, which is dependent on the light incident angle. More interestingly, the "on-off" motion of the SiO2/Au/PEN microparticles under vertical light irradiation results in the formation of the agglomeration with position and size precisely controlled by light. In addition, the resulting aggregation exhibits light-controlled dynamic migration behavior. The incident angle control thus opens up new opportunities for the motion control of the micromotors for diverse applications.
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Affiliation(s)
- Yunyu Sun
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014, China
| | - Jiwei Jiang
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Guangju Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014, China
| | - Ningning Yuan
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014, China
| | - Hui Zhang
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Bo Song
- Laboratory of Advanced Optoelectronic Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu 215123, China
| | - Bin Dong
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, China
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9
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Wang J, Xiong Z, Liu M, Li XM, Zheng J, Zhan X, Ding W, Chen J, Li X, Li XD, Feng SP, Tang J. Rational Design of Reversible Redox Shuttle for Highly Efficient Light-Driven Microswimmer. ACS NANO 2020; 14:3272-3280. [PMID: 32125822 DOI: 10.1021/acsnano.9b08799] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The light-driven micro/nanomotor (LMNM) is machinery that harvests photon energy and generates self-propulsion in varieties of liquid media. Though visions are made that these tiny swimming machines can serve future medicine for accurate drug delivery and noninvasive microsurgery, their biomedical application is still impeded by the insufficient propulsion efficiency. Here we provide a holistic model of LMNM by considering (i) photovoltaic, (ii) electrochemical, and (iii) electrokinetic processes therein. Such a quantitative model revealed the pivotal role of reaction kinetics and diffusion properties of shuttle ions in the propulsion efficiency of LMNM. With the guidance of this model, a group of ferrocene-based reversible redox shuttles, which generate slow-diffusion ions, was identified, showcasing a high locomotion velocity of ∼500 μm/s (∼100 body length per second) at an ultralow concentration (70 μM). Owing to the in-depth understanding of the fundamental energy conversion processes in LMNM, we anticipate that the development of other high-performance supporting chemicals and LMNM systems will be greatly motivated, foreseeing the advent of LMNM systems with superior efficiency.
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Affiliation(s)
- Jizhuang Wang
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, P. R. China
| | - Ze Xiong
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ming Liu
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xiao-Meng Li
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Jing Zheng
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xiaojun Zhan
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Weiting Ding
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Jianan Chen
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xuechen Li
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xiang David Li
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Shien-Ping Feng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Jinyao Tang
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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10
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Chen X, Zhou C, Peng Y, Wang Q, Wang W. Temporal Light Modulation of Photochemically Active, Oscillating Micromotors: Dark Pulses, Mode Switching, and Controlled Clustering. ACS APPLIED MATERIALS & INTERFACES 2020; 12:11843-11851. [PMID: 32092253 DOI: 10.1021/acsami.9b22342] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photochemically powered micromotors are prototype microrobots, and spatiotemporal control is pivotal for a wide range of potential applications. Although their spatial navigation has been extensively studied, temporal control of photoactive micromotors remains much less explored. Using Ag-based oscillating micromotors as a model system, a strategy is presented for the controlled modulation of their individual and collective dynamics via periodically switching illumination on and off. In particular, such temporal light modulation drives individual oscillating micromotors into a total of six regimes of distinct dynamics, as the light-toggling frequencies vary from 0 to 103 Hz. On an ensemble level, toggling light at 5 Hz gives rise to controlled, reversible clustering of oscillating micromotors and self-assembly of tracer microspheres into colloidal crystals. A qualitative mechanism based on Ag-catalyzed decomposition of H2O2 is given to account for some, but not all, of the above observations. This study might potentially inspire more sophisticated temporal control of micromotors and the development of smart, biomimetic materials that respond to environmental stimuli that not only change in space but also in time.
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Affiliation(s)
- Xi Chen
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Chao Zhou
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Yixin Peng
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Qizhang Wang
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Wei Wang
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
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11
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Chen X, Zhou C, Wang W. Colloidal Motors 101: A Beginner's Guide to Colloidal Motor Research. Chem Asian J 2019; 14:2388-2405. [DOI: 10.1002/asia.201900377] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/09/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Xi Chen
- School of Materials Science and EngineeringHarbin Institute of Technology (Shenzhen) G 908, HIT Campus, Xili University Town Shenzhen Guangdong China
| | - Chao Zhou
- School of Materials Science and EngineeringHarbin Institute of Technology (Shenzhen) G 908, HIT Campus, Xili University Town Shenzhen Guangdong China
| | - Wei Wang
- School of Materials Science and EngineeringHarbin Institute of Technology (Shenzhen) G 908, HIT Campus, Xili University Town Shenzhen Guangdong China
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12
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Esplandiu MJ, Zhang K, Fraxedas J, Sepulveda B, Reguera D. Unraveling the Operational Mechanisms of Chemically Propelled Motors with Micropumps. Acc Chem Res 2018; 51:1921-1930. [PMID: 30192137 DOI: 10.1021/acs.accounts.8b00241] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of effective autonomous micro- and nanomotors relies on controlling fluid motion at interfaces. One of the main challenges in the engineering of such artificial machines is the quest for efficient mechanisms to power them without using external driving forces. In the past decade, there has been an important increase of man-made micro- and nanomotors fueled by self-generated physicochemical gradients. Impressive proofs of concept of multitasking machines have been reported demonstrating their capabilities for a plethora of applications. While the progress toward applications is promising, there are still open questions on fundamental physicochemical aspects behind the mechanical actuation, which require more experimental and theoretical efforts. These efforts are not merely academic but will open the door for an efficient and practical implementation of such promising devices. In this Account, we focus on chemically driven motors whose motion is the result of a complex interplay of chemical reactions and (electro)hydrodynamic phenomena. A reliable study of these processes is rather difficult with mobile objects like swimming motors. However, pumps, which are the immobilized motor counterparts, emerge as simple manufacturing and well-defined platforms for a better experimental probing of the mechanisms and key parameters controlling the actuation. Here we review some recent studies using a new methodology that has turned out to be very helpful to characterize micropump chemomechanics. The aim was to identify the redox role of the motor components, to map the chemical reaction, and to quantify the relevant electrokinetic parameters (e.g., electric field and fluid flow). This was achieved by monitoring the velocity of differently charged tracers and by fluorescence imaging of the chemical species involved in the chemical reaction, for example, proton gradients. We applied these techniques to different systems of interest. First, we probed bimetallic pumps as counterparts of the pioneering bimetallic swimmers. We corroborated that fluid motion was due to a self-generated electro-osmotic mechanism driven by the redox decomposition of H2O2. In addition, we analyzed by simulations the key parameters that yield an optimized operation. Moreover, we accomplished a better assessment of the importance of surface chemistry on the metal electrochemical response, highlighting its relevance in controlling the redox role of the metals and motion direction. Second, we focused on metallic and semiconductor micropumps to analyze light-controlled motion mechanisms through photoelectrochemical decomposition of fuels. These pumps were driven by visible light and could operate using just water as fuel. In these systems, we found a very interesting competition between two different mechanisms for fluid propulsion, namely, light-activated electro-osmosis and light-insensitive diffusio-osmosis, stemming from different chemical pathways in the fuel decomposition. In this case, surface roughness becomes a pivotal parameter to enhance or depress one mechanism over the other. These examples demonstrate that pumps are practical platforms to explore operating mechanisms and to quantify their performance. Additionally, they are suitable systems to test novel fuels or motor materials. This knowledge is extensible to swimmers providing not only fundamental understanding of their locomotion mechanisms but also useful clues for their design and optimization.
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Affiliation(s)
- Maria Jose Esplandiu
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Kuan Zhang
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Jordi Fraxedas
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Borja Sepulveda
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - David Reguera
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain
- Universitat de Barcelona, Institute of Complex Systems (UBICS), C/Martí i Franquès 1, 08028 Barcelona, Spain
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13
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Kim C, Nonaka A, Bell JB, Garcia AL, Donev A. Fluctuating hydrodynamics of reactive liquid mixtures. J Chem Phys 2018; 149:084113. [PMID: 30193508 DOI: 10.1063/1.5043428] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Fluctuating hydrodynamics (FHD) provides a framework for modeling microscopic fluctuations in a manner consistent with statistical mechanics and nonequilibrium thermodynamics. This paper presents an FHD formulation for isothermal reactive incompressible liquid mixtures with stochastic chemistry. Fluctuating multispecies mass diffusion is formulated using a Maxwell-Stefan description without assuming a dilute solution, and momentum dynamics is described by a stochastic Navier-Stokes equation for the fluid velocity. We consider a thermodynamically consistent generalization for the law of mass action for non-dilute mixtures and use it in the chemical master equation (CME) to model reactions as a Poisson process. The FHD approach provides remarkable computational efficiency over traditional reaction-diffusion master equation methods when the number of reactive molecules is large, while also retaining accuracy even when there are as few as ten reactive molecules per hydrodynamic cell. We present a numerical algorithm to solve the coupled FHD and CME equations and validate it on both equilibrium and nonequilibrium problems. We simulate a diffusively driven gravitational instability in the presence of an acid-base neutralization reaction, starting from a perfectly flat interface. We demonstrate that the coupling between velocity and concentration fluctuations dominates the initial growth of the instability.
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Affiliation(s)
- Changho Kim
- Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Andy Nonaka
- Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - John B Bell
- Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Alejandro L Garcia
- Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192, USA
| | - Aleksandar Donev
- Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012, USA
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14
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Ning H, Zhang Y, Zhu H, Ingham A, Huang G, Mei Y, Solovev AA. Geometry Design, Principles and Assembly of Micromotors. MICROMACHINES 2018; 9:E75. [PMID: 30393351 PMCID: PMC6187850 DOI: 10.3390/mi9020075] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 01/19/2023]
Abstract
Discovery of bio-inspired, self-propelled and externally-powered nano-/micro-motors, rotors and engines (micromachines) is considered a potentially revolutionary paradigm in nanoscience. Nature knows how to combine different elements together in a fluidic state for intelligent design of nano-/micro-machines, which operate by pumping, stirring, and diffusion of their internal components. Taking inspirations from nature, scientists endeavor to develop the best materials, geometries, and conditions for self-propelled motion, and to better understand their mechanisms of motion and interactions. Today, microfluidic technology offers considerable advantages for the next generation of biomimetic particles, droplets and capsules. This review summarizes recent achievements in the field of nano-/micromotors, and methods of their external control and collective behaviors, which may stimulate new ideas for a broad range of applications.
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Affiliation(s)
- Huanpo Ning
- Department of Materials Science, Fudan University, 220 Handan Road, 200433 Shanghai, China.
| | - Yan Zhang
- Department of Materials Science, Fudan University, 220 Handan Road, 200433 Shanghai, China.
| | - Hong Zhu
- Department of Materials Science, Fudan University, 220 Handan Road, 200433 Shanghai, China.
| | - Andreas Ingham
- Department of Biology, University of Copenhagen, 5 Ole Maaløes Vej, DK-2200, 1165 København, Denmark.
| | - Gaoshan Huang
- Department of Materials Science, Fudan University, 220 Handan Road, 200433 Shanghai, China.
| | - Yongfeng Mei
- Department of Materials Science, Fudan University, 220 Handan Road, 200433 Shanghai, China.
| | - Alexander A Solovev
- Department of Materials Science, Fudan University, 220 Handan Road, 200433 Shanghai, China.
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15
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Zhang K, Fraxedas J, Sepulveda B, Esplandiu MJ. Photochemically Activated Motors: From Electrokinetic to Diffusion Motion Control. ACS APPLIED MATERIALS & INTERFACES 2017; 9:44948-44953. [PMID: 29199814 DOI: 10.1021/acsami.7b15855] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-propelled micro/nanomotors that can transform chemical energy from the surrounding environment into mechanical motion are cutting edge nanotechnologies with potential applications in biomedicine and environmental remediation. These applications require full understanding of the propulsion mechanisms to improve the performance and controllability of the motors. In this work, we demonstrate that there are two competing chemomechanical mechanisms at semiconductor/metal (Si/Pt) micromotors in a pump configuration under visible light exposure. The first propulsion mechanism is driven by an electro-osmotic process stemmed from a photoactivation reaction mediated by H2O2, which takes place in two separated redox reactions at the Si and Pt interfaces. One reaction involves the oxidation of H2O2 at the silicon side, and the other the H2O2 reduction at the metal side. The second mechanism is not light responsive and is triggered by the redox decomposition of H2O2 exclusively at the Pt surface. We show that it is possible to enhance/suppress one mechanism over the other by tuning the surface roughness of the micromotor metal. More specifically, the actuation mechanism can be switched from light-controlled electrokinetics to light-insensitive diffusio-osmosis by only increasing the metal surface roughness. The different actuation mechanisms yield strikingly different fluid flow velocities, electric fields, and light sensitivities. Consequently, these findings are very relevant and can have a remarkable impact on the design and optimization of photoactivated catalytic devices and, in general, on bimetallic or insulating-metallic motors.
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Affiliation(s)
- Kuan Zhang
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Universitat Autònoma de Barcelona (UAB) , Bellaterra E-08193, Spain
| | - Jordi Fraxedas
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Borja Sepulveda
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Maria J Esplandiu
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Universitat Autònoma de Barcelona (UAB) , Bellaterra E-08193, Spain
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16
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Weistuch C, Pressé S. Spatiotemporal Organization of Catalysts Driven by Enhanced Diffusion. J Phys Chem B 2017; 122:5286-5290. [DOI: 10.1021/acs.jpcb.7b06868] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- C. Weistuch
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - S. Pressé
- Department of Physics, IUPUI Indianapolis, Indianapolis, Indiana 46202, United States
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17
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Altemose A, Sánchez‐Farrán MA, Duan W, Schulz S, Borhan A, Crespi VH, Sen A. Chemically Controlled Spatiotemporal Oscillations of Colloidal Assemblies. Angew Chem Int Ed Engl 2017; 56:7817-7821. [DOI: 10.1002/anie.201703239] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Alicia Altemose
- Department of Chemistry The Pennsylvania State University University Park PA 16802 USA
| | | | - Wentao Duan
- Department of Chemistry The Pennsylvania State University University Park PA 16802 USA
| | - Steve Schulz
- Manheim Township High School Lancaster PA 17606 USA
| | - Ali Borhan
- Department of Chemical Engineering, The Pennsylvania State University University Park PA 16802 USA
| | - Vincent H. Crespi
- Departments of Physics, Chemistry, and Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Ayusman Sen
- Department of Chemistry The Pennsylvania State University University Park PA 16802 USA
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18
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Altemose A, Sánchez‐Farrán MA, Duan W, Schulz S, Borhan A, Crespi VH, Sen A. Chemically Controlled Spatiotemporal Oscillations of Colloidal Assemblies. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201703239] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Alicia Altemose
- Department of Chemistry The Pennsylvania State University University Park PA 16802 USA
| | | | - Wentao Duan
- Department of Chemistry The Pennsylvania State University University Park PA 16802 USA
| | - Steve Schulz
- Manheim Township High School Lancaster PA 17606 USA
| | - Ali Borhan
- Department of Chemical Engineering, The Pennsylvania State University University Park PA 16802 USA
| | - Vincent H. Crespi
- Departments of Physics, Chemistry, and Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Ayusman Sen
- Department of Chemistry The Pennsylvania State University University Park PA 16802 USA
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19
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Brown AT, Poon WCK, Holm C, de Graaf J. Ionic screening and dissociation are crucial for understanding chemical self-propulsion in polar solvents. SOFT MATTER 2017; 13:1200-1222. [PMID: 28098324 DOI: 10.1039/c6sm01867j] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Polar solvents like water support the bulk dissociation of themselves and their solutes into ions, and the re-association of these ions into neutral molecules in a dynamic equilibrium, e.g., H2O2 ⇌ H+ + HO2-. Using continuum theory, we study the influence of these association-dissociation reactions on the self-propulsion of colloids driven by surface chemical reactions (chemical swimmers). We find that association-dissociation reactions should have a strong influence on swimmers' behaviour, and therefore should be included in future modelling. In particular, such bulk reactions should permit charged swimmers to propel electrophoretically even if all species involved in the surface reactions are neutral. The bulk reactions also significantly modify the predicted speed of chemical swimmers propelled by ionic currents, by up to an order of magnitude. For swimmers whose surface reactions produce both anions and cations (ionic self-diffusiophoresis), the bulk reactions produce an additional reactive screening length, analogous to the Debye length in electrostatics. This in turn leads to an inverse relationship between swimmer radius and swimming speed, which could provide an alternative explanation for recent experimental observations on Pt-polystyrene Janus swimmers [S. Ebbens et al., Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys., 2012, 85, 020401]. We also use our continuum theory to investigate the effect of the Debye screening length itself, going beyond the infinitely-thin-screening-length approximation used by previous analytical theories. We identify significant departures from this limiting behaviour for micron-sized swimmers under typical experimental conditions and find that the approximation fails entirely for nanoscale swimmers.
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Affiliation(s)
- Aidan T Brown
- SUPA, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
| | - Wilson C K Poon
- SUPA, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
| | - Christian Holm
- Institute for Computational Physics, Stuttgart University, Pfaffenwaldring 27, D-70569 Stuttgart, Germany
| | - Joost de Graaf
- SUPA, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK. and Institute for Computational Physics, Stuttgart University, Pfaffenwaldring 27, D-70569 Stuttgart, Germany
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20
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Liu C, Zhou C, Wang W, Zhang HP. Bimetallic Microswimmers Speed Up in Confining Channels. PHYSICAL REVIEW LETTERS 2016; 117:198001. [PMID: 27858454 DOI: 10.1103/physrevlett.117.198001] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Indexed: 06/06/2023]
Abstract
Synthetic microswimmers are envisioned to be useful in numerous applications, many of which occur in tightly confined spaces. It is therefore important to understand how confinement influences swimmer dynamics. Here we study the motility of bimetallic microswimmers in linear and curved channels. Our experiments show swimmer velocities increase, up to 5 times, with the degree of confinement, and the relative velocity increase depends weakly on the fuel concentration and ionic strength in solution. Experimental results are reproduced in a numerical model which attributes the swimmer velocity increase to electrostatic and electrohydrodynamic boundary effects. Our work not only helps to elucidate the confinement effect of phoretic swimmers, but also suggests that spatial confinement may be used as an effective control method for them.
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Affiliation(s)
- Chang Liu
- Department of Physics and Astronomy and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chao Zhou
- School of Material Science and Engineering, Harbin Institute of Technology, Shenzhen Graduate School, Shenzhen 518055, China
| | - Wei Wang
- School of Material Science and Engineering, Harbin Institute of Technology, Shenzhen Graduate School, Shenzhen 518055, China
- Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - H P Zhang
- Department of Physics and Astronomy and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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