1
|
Paul A, Aluru NR. Nanoscale electrohydrodynamic ion transport: Influences of channel geometry and polarization-induced surface charges. Phys Rev E 2024; 109:025105. [PMID: 38491612 DOI: 10.1103/physreve.109.025105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/19/2024] [Indexed: 03/18/2024]
Abstract
Electrohydrodynamic ion transport has been studied in nanotubes, nanoslits, and nanopores to mimic the advanced functionalities of biological ion channels. However, probing how the intricate interplay between the electrical and mechanical interactions affects ion conduction in asymmetric nanoconduits presents further obstacles. Here, ion transport across a conical nanopore embedded in a polarizable membrane under an electric field and pressure is analyzed by numerically solving a continuum model based on the Poisson, Nernst-Planck, and Navier-Stokes equations. We report an anomalous ionic current depletion, of up to 75%, and an unexpected rise in current rectification when pressure is exerted along the external electric field. Membrane polarization is revealed as the prerequisite to obtain this previously undetected electrohydrodynamic coupling. The electric field induces large surface charges at the pore tip due to its conical shape, creating nonuniform electrical double layers (EDL) with a massive accumulation of electrolyte ions near the orifice. Once applied, the pressure distorts the quasiequilibrium distribution of the EDL ions to influence the nanopore conductivity. Our fundamental approach to inspect the effect of pressure on the channel EDL (and thus ionic conductance) in contrast to its effect on the current arising from the hydrodynamic streaming of ions further explains the pressure-sensitive ion transport in different nanochannels and physical regimes manifested in past experiments, including the hitherto inexplicit mechanism behind the mechanically activated ion transport in carbon nanotubes. This enhances our broad understanding of nanoscale electrohydrodynamic ion transport, yielding a platform to build nanofluidic devices and ionic circuits with more robust and tunable responses to electrical and mechanical stimuli.
Collapse
Affiliation(s)
- Arghyadeep Paul
- Department of Mechanical Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - N R Aluru
- Walker Department of Mechanical Engineering, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
| |
Collapse
|
2
|
Trivedi M, Gupta R, Nirmalkar N. Electroosmotic transport and current rectification of viscoelastic electrolyte in a conical pore nanomembrane. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.120755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
3
|
Chang CC. Asymmetric Electrokinetic Energy Conversion in Slip Conical Nanopores. NANOMATERIALS 2022; 12:nano12071100. [PMID: 35407218 PMCID: PMC9000662 DOI: 10.3390/nano12071100] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 02/08/2023]
Abstract
Ion current rectification (ICR) phenomena in asymmetric nanofluidic structures, such as conical-shaped nanopores and funnel-shaped nanochannels, have been widely investigated in recent decades. To date, the effect of asymmetric nanofluidic structures on electrokinetic power generation driven by the streaming current/potential has not been explored. Accordingly, this study employed a numerical model based on the Poisson equation, Nernst–Planck equation, and Navier–Stokes equation to investigate the electrokinetic energy conversion (EKEC) in a conical nanopore while considering hydrodynamic slippage. The results indicated that the asymmetric characteristics of streaming current (short-circuit current), streaming potential (open-circuit voltage), maximum power generation, maximum conversion efficiency, and flow rate were observed in conical nanopores under the forward pressure bias (tip-to-base direction) and reverse pressure bias (base-to-tip direction) once the nonequilibrium ion concentration polarization (ICP) became considerable. The rectification behaviors in the streaming current, maximum power, and maximum conversion efficiency were all shown to be opposite to those of the well-known ICR in conical nanopores. In other words, the reverse pressure bias revealed a higher EKEC performance than the forward pressure bias. It was concluded that the asymmetric behavior in EKEC is attributed to the asymmetric electrical resistance resulting from asymmetric ion depletion and ion enrichment. Particularly, it was found that the decrease in electrical resistance (i.e., the change in electrical resistance dominated by the ion enrichment) observed in the reverse pressure bias enhanced the maximum power and maximum conversion efficiency. The asymmetric EKEC characteristics became more significant with increasing slip length, surface charge density, cone angle, and pressure bias, especially at lower salt concentrations. The present findings provide useful information for the future development of EKEC in engineered membranes with asymmetric nanopores.
Collapse
Affiliation(s)
- Chih-Chang Chang
- Department of Industrial Technology Education, National Kaohsiung Normal University, Kaohsiung 824, Taiwan
| |
Collapse
|
4
|
High‐Efficient and Dosage‐Controllable Intracellular Cargo Delivery through Electrochemical Metal–Organic Hybrid Nanogates. SMALL SCIENCE 2021. [DOI: 10.1002/smsc.202100069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
|
5
|
Jiao Y, Zhao C, Yang C, Kang Y, Gao X, Wang H, Song L, He B. A numerical study on ion concentration polarization and electric circuit performance of an electrokinetic battery. Electrophoresis 2020; 41:811-820. [PMID: 32097991 DOI: 10.1002/elps.201900466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/13/2020] [Accepted: 02/19/2020] [Indexed: 11/11/2022]
Abstract
Ion concentration polarization (ICP) imposes remarkable adverse effects on the energy conversion performance of the pressure-driven electrokinetic (EK) flows through a capillary system that can be equivalently treated as a battery. An optimized dimensionless numerical method is proposed in this study to investigate the causes and the effects of the ICP. Results show that remarkable ICP phenomena are induced under certain conditions such as high applied pressure, high surface charge density, and small inversed Debye length at dimensionless values of 6000, -10, and 0.5. Meanwhile, different factors influence the ICP and the corresponding electric properties in different ways. Particularly for the overall electric resistance, the applied pressure and the surface charge density mainly affect the variation amplitude and the level of the overall electric resistance when varying the output electric potential, respectively. Differently, the Debye length affects the overall electric resistance in both aspects. Ultimately, the induced ICP leads to significant nonlinear current-potential curves.
Collapse
Affiliation(s)
- Yanmei Jiao
- School of Physical and Mathematical Sciences, Nanjing Tech University, Nanjing, P. R. China
| | - Cunlu Zhao
- Key Laboratory of Thermo-Fluid Science and Engineering of MOE, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Chun Yang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang, Singapore
| | - Yuejun Kang
- Institute for Clean Energy and Advanced Materials, Southwest University, Chongqing, P. R. China
| | - Xiumin Gao
- School of Physical and Mathematical Sciences, Nanjing Tech University, Nanjing, P. R. China
| | - Hui Wang
- School of Physical and Mathematical Sciences, Nanjing Tech University, Nanjing, P. R. China
| | - Linhui Song
- School of Physical and Mathematical Sciences, Nanjing Tech University, Nanjing, P. R. China
| | - Bin He
- School of Physical and Mathematical Sciences, Nanjing Tech University, Nanjing, P. R. China
| |
Collapse
|
6
|
Malgaretti P, Janssen M, Pagonabarraga I, Rubi JM. Driving an electrolyte through a corrugated nanopore. J Chem Phys 2019; 151:084902. [DOI: 10.1063/1.5110349] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Paolo Malgaretti
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Mathijs Janssen
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Ignacio Pagonabarraga
- Departament de Fisica de la Materia Condensada, Universitat de Barcelona, Carrer Martí i Franqués, 08028 Barcelona, Spain
- CECAM, Centre Européeen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne, Batochime, Avenue Forel 2, 1015 Lausanne, Switzerland
- Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Spain
| | - J. Miguel Rubi
- Departament de Fisica de la Materia Condensada, Universitat de Barcelona, Carrer Martí i Franqués, 08028 Barcelona, Spain
| |
Collapse
|
7
|
Pevarnik M, Cui W, Yemenicioglu S, Rofeh J, Theogarajan L. Solid-state nanopore based biomimetic voltage gated ion channels. BIOINSPIRATION & BIOMIMETICS 2017; 12:066008. [PMID: 28726670 DOI: 10.1088/1748-3190/aa811b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Voltage gating is essential to the computational ability of neurons. We show this effect can be mimicked in a solid-state nanopore by functionalizing the pore interior with a redox active molecule. We study the integration of an active biological molecule-a quinone-into a solid state nanopore, and its subsequent induced voltage gating. We show that the voltage gating effect mimics biological gating systems in its classic sigmoidal voltage response, unlike previous synthetic voltage gating systems. Initially, the quinone undergoes a reduction due to radicals in the bulk solution, and is converted to the hydroquinone state. Upon deprontonation the hydroquinone then acts as a charged nanomechanical arm, which opens the channel under the applied potential. We establish that the quinone gains a single net charge when the pH inside of the nanopore reaches its pKa value, and explore factors that influence the net pH in the middle of the pore. Using a combination of theory, experiment and simulation, we conclude that concentration polarization and a shift of the pH inside of the channel is the main cause of this gating effect.
Collapse
Affiliation(s)
- Matthew Pevarnik
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106-9560, United States of America. Department of Science and Math, Regent University, Virginia Beach, VA 23464-5037, United States of America
| | | | | | | | | |
Collapse
|
8
|
Lan WJ, Edwards MA, Luo L, Perera RT, Wu X, Martin CR, White HS. Voltage-Rectified Current and Fluid Flow in Conical Nanopores. Acc Chem Res 2016; 49:2605-2613. [PMID: 27689816 DOI: 10.1021/acs.accounts.6b00395] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ion current rectification (ICR) refers to the asymmetric potential-dependent rate of the passage of solution ions through a nanopore, giving rise to electrical current-voltage characteristics that mimic those of a solid-state electrical diode. Since the discovery of ICR in quartz nanopipettes two decades ago, synthetic nanopores and nanochannels of various geometries, fabricated in membranes and on wafers, have been extensively investigated to understand fundamental aspects of ion transport in highly confined geometries. It is now generally accepted that ICR requires an asymmetric electrical double layer within the nanopore, producing an accumulation or depletion of charge-carrying ions at opposite voltage polarities. Our research groups have recently explored how the voltage-dependent ion distributions and ICR within nanopores can induce novel nanoscale flow phenomena that have applications in understanding ionics in porous materials used in energy storage devices, chemical sensing, and low-cost electrical pumping of fluids. In this Account, we review our most recent investigations on this topic, based on experiments using conical nanopores (10-300 nm tip opening) fabricated in thin glass, mica, and polymer membranes. Measurable fluid flow in nanopores can be induced either using external pressure forces, electrically via electroosmotic forces, or by a combination of these two forces. We demonstrate that pressure-driven flow can greatly alter the electrical properties of nanopores and, vice versa, that the nonlinear electrical properties of conical nanopores can impart novel and useful flow phenomena. Electroosmotic flow (EOF), which depends on the magnitude of the ion fluxes within the double layer of the nanopore, is strongly coupled to the accumulation/depletion of ions. Thus, the same underlying cause of ICR also leads to EOF rectification, i.e., unequal flows occurring for the same voltage but opposite polarities. EOF rectification can be used to electrically pump fluids with very precise control across membranes containing conical pores via the application of a symmetric sinusoidal voltage. The combination of pressure and asymmetric EOF can also provide a means to generate new nanopore electrical behaviors, including negative differential resistance (NDR), in which the current through a conical pore decreases with increasing driving force (applied voltage), similar to solid-state tunnel diodes. NDR results from a positive feedback mechanism between the ion distributions and EOF, yielding a true bistability in both fluid flow and electrical current at a critical applied voltage. Nanopore-based NDR is extremely sensitive to the surface charge near the nanopore opening, suggesting possible applications in chemical sensing.
Collapse
Affiliation(s)
- Wen-Jie Lan
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Martin A. Edwards
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Long Luo
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Rukshan T. Perera
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Xiaojian Wu
- Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Charles R. Martin
- Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Henry S. White
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| |
Collapse
|
9
|
Wu X, Ramiah Rajasekaran P, Martin CR. An Alternating Current Electroosmotic Pump Based on Conical Nanopore Membranes. ACS NANO 2016; 10:4637-43. [PMID: 27046145 DOI: 10.1021/acsnano.6b00939] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Electroosmotic flow (EOF) is used to pump solutions through microfluidic devices and capillary electrophoresis columns. We describe here an EOF pump based on membrane EOF rectification, an electrokinetic phenomenon we recently described. EOF rectification requires membranes with asymmetrically shaped pores, and conical pores in a polymeric membrane were used here. We show here that solution flow through the membrane can be achieved by applying a symmetrical sinusoidal voltage waveform across the membrane. This is possible because the alternating current (AC) carried by ions through the pore is rectified, and we previously showed that rectified currents yield EOF rectification. We have investigated the effect of both the magnitude and frequency of the voltage waveform on flow rate through the membrane, and we have measured the maximum operating pressure. Finally, we show that operating in AC mode offers potential advantages relative to conventional DC-mode EOF pumps.
Collapse
Affiliation(s)
- Xiaojian Wu
- Department of Chemistry, University of Florida , Gainesville, Florida 32611-7200, United States
| | | | - Charles R Martin
- Department of Chemistry, University of Florida , Gainesville, Florida 32611-7200, United States
| |
Collapse
|