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Sun Y, Jiang R, Hu L, Song Y, Li M. Electrokinetic transport phenomena in nanofluidics and their applications. Electrophoresis 2023; 44:1756-1773. [PMID: 37438973 DOI: 10.1002/elps.202300115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/23/2023] [Accepted: 06/28/2023] [Indexed: 07/14/2023]
Abstract
Much progress has been made in the electrokinetic phenomena inside nanochannels in the last decades. As the dimensions of the nanochannels are compatible to that of the electric double layer (EDL), the electrokinetics inside nanochannels indicate many unexpected behaviors, which show great potential in the fields of material science, biology, and chemistry. This review summarizes the recent development of nanofluidic electrokinetics in both fundamental and applied research. First, the techniques for constructing nanochannels are introduced to give a guideline for choosing the optimal fabrication technique based on the specific feature of the nanochannel. Then, the theories and experimental investigations of the EDL, electroosmotic flow, and electrophoresis of nanoparticles inside the nanochannels are discussed. Furthermore, the applications of nanofluidic electrokinetics in iontronics, sensing, and biomolecule separation fields are summarized. In Section 5, some critical challenges and the perspective on the future development of nanofluidic electrokinetics are briefly proposed.
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Affiliation(s)
- Ya Sun
- Department of Environmental Science and Engineering, Dalian Maritime University, Dalian, Liaoning, P. R. China
| | - Rui Jiang
- Department of Marine Engineering, Dalian Maritime University, Dalian, Liaoning, P. R. China
| | - Lide Hu
- Department of Marine Engineering, Dalian Maritime University, Dalian, Liaoning, P. R. China
| | - Yongxin Song
- Department of Marine Engineering, Dalian Maritime University, Dalian, Liaoning, P. R. China
| | - Mengqi Li
- Department of Marine Engineering, Dalian Maritime University, Dalian, Liaoning, P. R. China
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Feng N, Peng X, Wang Z, Yu X, Shentu X, Chen Y. Label-Free Microchannel Immunosensor Based on Antibody–Antigen Biorecognition-Induced Charge Quenching. Anal Chem 2022; 94:16778-16786. [DOI: 10.1021/acs.analchem.2c03675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Niu Feng
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan430070, Hubei, China
| | - Xuewen Peng
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan430070, Hubei, China
| | - Zhipan Wang
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan430070, Hubei, China
| | - Xiaoping Yu
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Science, China Jiliang University, Hangzhou310000, Zhejiang, China
| | - Xuping Shentu
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Science, China Jiliang University, Hangzhou310000, Zhejiang, China
| | - Yiping Chen
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan430070, Hubei, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Pengfei Road, Dapeng District, Shenzhen518120, Guangdong, China
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Wu P, Sun T, Jiang X. Non-monotonic variation of flow strength in nanochannels grafted with end-charged polyelectrolyte layers. RSC Adv 2022; 12:4061-4071. [PMID: 35425443 PMCID: PMC8981053 DOI: 10.1039/d1ra06601c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/25/2021] [Indexed: 11/30/2022] Open
Abstract
The electrokinetic transport of fluids, also called the electroosmotic flow (EOF), in micro/nanoscale devices occurs in promising applications such as electrokinetic energy conversion (EKEC) systems. Recently, EKEC systems grafted with end-charged polyelectrolyte (PE) layers (PELs) have been reported to exhibit higher efficiencies than those of intrinsic systems. Understanding the interplay between the end-charged PELs and electrical double layers (EDLs) on the EOF is crucial for designing highly efficient EKEC systems. The interplay between the end-charged PELs and EDLs on the strength of the EOF (V0) is studied by explicitly modeling the EOF through nanochannels grafted with end-charged PELs using atomic simulations. The variation of V0 is examined for nanochannels grafted with PELs at various separations (d = 3.5–0.4 nm) to cover various conformations of PEs, inlcuding mushroom, semi-dilute brushes, and concentrated brushes. We find that V0 follows a non-monotonic variation as d decreases and this is correlated with the conformation of the PEs. Specifically, as d decreases, V0 decreases first in the mushroom regime (d = 3.5–2.0 nm), and then V0 increases in the concentrated brush regime (d = 0.75–0.4 nm). Navigated by the continuum Navier–Stokes–Brinkman model, the above observations are rationalized by the competition between the driving effect from the spatial shift of ions in EDLs and the drag effect from PELs. The insights obtained in this work are important to guide the design of highly efficient EKEC systems by grafting end-charged PELs onto channel surfaces. A non-monotonic variation of the strength of electroosmotic flow (V0) is reported for the electroosmotic flow through nanochannels grafted with end-charged polyelectrolytes at various separation using atomic simulations.![]()
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Affiliation(s)
- Peng Wu
- College of Energy and Power Engineering, Inner Mongolia University of Technology, Inner Mongolia, Hohhot, 010051, China
- China–EU Institute of Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Tao Sun
- China–EU Institute of Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Xikai Jiang
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China
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Sachar HS, Pial TH, Sivasankar VS, Das S. Simultaneous Energy Generation and Flow Enhancement ( Electroslippage Effect) in Polyelectrolyte Brush Functionalized Nanochannels. ACS NANO 2021; 15:17337-17347. [PMID: 34605243 DOI: 10.1021/acsnano.1c05056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Energy generation through nanofluidics is a topic of great nanotechnological relevance. Here, we conduct all-atom molecular dynamics (MD) simulations of the transport of water and ions in a pressure-driven flow in nanochannels grafted with charged polyelectrolyte (PE) brushes and discover the possibility of simultaneous electrokinetic energy generation and flow enhancement (henceforth denoted as the electroslippage effect). Such PE-brush-functionalized nanochannels have been recently shown to demonstrate an overscreening (OS) effect (characterized by the presence of a greater number of screening counterions within the PE brush layer than needed to screen the PE brush charges), a consequent presence of excess co-ions within the PE brush-free bulk, and a co-ion-driven electroosmotic (EOS) transport in the presence of small to moderate applied axial electric fields. In this study, however, we find that the streaming current, which represents the current generated by the flow-driven downstream advection of the charge imbalance present within the electric double layer (EDL) that screens the PE brush charges, is governed by the migration of the counterions. This stems from the fact that the highest contribution to the overall streaming current arises from the region near the PE brush-water interface (where there is an excess of counterions), while the brush-free bulk yields a hitherto unreported, but small, co-ion-dictated streaming current. This downstream advection of the charge imbalance (and the resultant counterion-driven streaming current) eventually leads to the development of an electric field (streaming electric field) in the direction that is opposite the direction of the counterion-driven streaming current. The streaming current and the streaming electric field interact to generate the electrokinetic energy. Equally important, this streaming electric field induces an EOS transport, which becomes co-ion-driven, due to the presence of excess co-ions in the brush-free bulk. For the case of nanochannels grafted with negatively charged PE brushes, the streaming electric field will be in a direction that is opposite that of the pressure-driven transport, and hence the co-ion (or anion) driven EOS flow will be in the same direction as the pressure-driven transport. On the other hand, for the case of nanochannels grafted with positively charged PE brushes, the streaming electric field will be in the same direction as the pressure-driven flow, and hence the co-ion (or cation) driven EOS flow, will again be in the same direction as the pressure-driven flow. Therefore, whenever there occurs a presence of the OS and the resulting co-ion-driven EOS transport in PE brush grafted nanochannels, regardless of the sign of the charges of the PE brushes, this EOS transport will always aid the pressure-driven transport and will cause the most fascinating increase in the net volume flow rate across the nanochannel cross section, which is the electroslippage effect.
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Affiliation(s)
| | | | | | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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Li J, Li D. A surface charge governed nanofluidic diode based on a single polydimethylsiloxane (PDMS) nanochannel. J Colloid Interface Sci 2021; 596:54-63. [PMID: 33831750 DOI: 10.1016/j.jcis.2021.03.126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/20/2021] [Accepted: 03/22/2021] [Indexed: 11/16/2022]
Abstract
HYPOTHESIS Nanofluidic diodes have attracted intense attention recently. Commonly used materials to design these devices are membrane-based short nanopores and aligned Carbon nanotube bundles. It is highly desirable and very challenging to develop a nanofluidic diode based on a single PDMS nanochannel which is easier to be introduced into an integrated electronic system on a chip. Layer-by-layer (LBL) deposition of charged polyelectrolytes can change the size and surface properties of PDMS nanochannels that provides new possibilities to develop high-performance nanofluidic based on PDMS nanochannels. EXPERIMENTS A novel design of nanofluidic diode is presented by controlling the surface charges and sizes of single PDMS nanochannels by surface modification using polyelectrolytes. Polybrene (PB) and Dextran sulfate (DS) are used to reduce the PDMS nanochannel size to meet the requirement of ion gating by LBL method and generate opposite surface charges at the ends of nanochannels. The parameters of such a nanofluidic diode are investigated systematically. FINDINGS This nanofluidic diode developed in this work has high effective current rectification performance. The rectification ratio can be as high as 218 which is the best ever reported in PB/DS modified nanochannels. This rectification ratio reduces with high voltage frequency and ionic concentration whereas increases in shorter nanochannels.
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Affiliation(s)
- Jun Li
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Dongqing Li
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
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Transdermal electroosmotic flow generated by a porous microneedle array patch. Nat Commun 2021; 12:658. [PMID: 33510169 PMCID: PMC7843990 DOI: 10.1038/s41467-021-20948-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 12/22/2020] [Indexed: 01/22/2023] Open
Abstract
A microneedle array is an attractive option for a minimally invasive means to break through the skin barrier for efficient transdermal drug delivery. Here, we report the applications of solid polymer-based ion-conductive porous microneedles (PMN) containing interconnected micropores for improving iontophoresis, which is a technique of enhancing transdermal molecular transport by a direct current through the skin. The PMN modified with a charged hydrogel brings three innovative advantages in iontophoresis at once: (1) lowering the transdermal resistance by low-invasive puncture of the highly resistive stratum corneum, (2) transporting of larger molecules through the interconnected micropores, and (3) generating electroosmotic flow (EOF). In particular, the PMN-generated EOF greatly enhances the transdermal molecular penetration or extraction, similarly to the flow induced by external pressure. The enhanced efficiencies of the EOF-assisted delivery of a model drug (dextran) and of the extraction of glucose are demonstrated using a pig skin sample. Furthermore, the powering of the PMN-based transdermal EOF system by a built-in enzymatic biobattery (fructose / O2 battery) is also demonstrated as a possible totally organic iontophoresis patch.
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Le THH, Shimizu H, Morikawa K. Advances in Label-Free Detections for Nanofluidic Analytical Devices. MICROMACHINES 2020; 11:mi11100885. [PMID: 32977690 PMCID: PMC7598655 DOI: 10.3390/mi11100885] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022]
Abstract
Nanofluidics, a discipline of science and engineering of fluids confined to structures at the 1-1000 nm scale, has experienced significant growth over the past decade. Nanofluidics have offered fascinating platforms for chemical and biological analyses by exploiting the unique characteristics of liquids and molecules confined in nanospaces; however, the difficulty to detect molecules in extremely small spaces hampers the practical applications of nanofluidic devices. Laser-induced fluorescence microscopy with single-molecule sensitivity has been so far a major detection method in nanofluidics, but issues arising from labeling and photobleaching limit its application. Recently, numerous label-free detection methods have been developed to identify and determine the number of molecules, as well as provide chemical, conformational, and kinetic information of molecules. This review focuses on label-free detection techniques designed for nanofluidics; these techniques are divided into two groups: optical and electrical/electrochemical detection methods. In this review, we discuss on the developed nanofluidic device architectures, elucidate the mechanisms by which the utilization of nanofluidics in manipulating molecules and controlling light-matter interactions enhances the capabilities of biological and chemical analyses, and highlight new research directions in the field of detections in nanofluidics.
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Affiliation(s)
- Thu Hac Huong Le
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Correspondence: (T.H.H.L.); (H.S.); (K.M.)
| | - Hisashi Shimizu
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Correspondence: (T.H.H.L.); (H.S.); (K.M.)
| | - Kyojiro Morikawa
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Correspondence: (T.H.H.L.); (H.S.); (K.M.)
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Babar M, Dubey K, Bahga SS. Effect of surface conduction-induced electromigration on current monitoring method for electroosmotic flow measurement. Electrophoresis 2019; 41:570-577. [PMID: 31661562 DOI: 10.1002/elps.201900308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/14/2019] [Accepted: 10/23/2019] [Indexed: 11/10/2022]
Abstract
Current monitoring method for measurement of EOF in microchannels involves measurement of time-varying current while an electrolyte displaces another electrolyte having different conductivity due to EOF. The basic premise of the current monitoring method is that an axial gradient in conductivity of a binary electrolyte in a microchannel advects only due to EOF. In the current work, using theory and experiments, we show that this assumption is not valid for low concentration electrolytes and narrow microchannels wherein surface conduction is comparable with bulk conduction. We show that in presence of surface conduction, a gradient in conductivity of binary electrolyte not only advects with EOF but also undergoes electromigration. This electromigration phenomenon is nonlinear and is characterized by propagation of shock and rarefaction waves in ion concentrations. Consequently, in presence of surface conduction, the current-time relationships for forward and reverse displacement in the current monitoring method are asymmetric and the displacement time is also direction dependent. To quantify the effect of surface conduction, we present analytical expressions for current-time relationship in the regime when surface conduction is comparable to bulk conduction. We validate these relations with experimental data by performing a series of current monitoring experiments in a glass microfluidic chip at low electrolyte concentrations. The experimentally validated analytical expressions for current-time relationships presented in this work can be used to correctly estimate EOF using the current monitoring method when surface conduction is not negligible.
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Affiliation(s)
- Mohammad Babar
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Delhi, India
| | - Kaushlendra Dubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Delhi, India
| | - Supreet Singh Bahga
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Delhi, India
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