Recent advances in ionic current rectification based nanopore sensing: a mini-review

Zhang, Shujie; Chen, Wei; Song, Lai-Bo; Wang, Xiaohong; Sun, Wenzhe; Song, Pengyun; Ashraf, Ghazala; Liu, Bo; Zhao, Yuan‐Di

doi:10.1016/j.snr.2021.100042

Cited by 26 publications

(31 citation statements)

References 87 publications

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“…The classical form of nanopore sensing is the resistive-pulse technique, which utilizes short-lived blockages of the nanopore as an analyte translocates, resulting in a detectable decrease in the steady-state current . This technique has found wide applications ranging from the detection of various analytes such as metal ions, molecules, nucleotides, and proteins, to DNA sequencing. − Another more recent nanopore sensing platform is ionic current rectifying (ICR) nanopores . Nanopores with a charged surface and an asymmetry, which can be either an asymmetric geometry (such as a conical nanopore) or asymmetric surface charge distribution, have a non-Ohmic current–voltage curve, where the current measured at one potential is not the same as the current measured at the equal but opposite potential. − Such a current–voltage curve is said to be rectified, and the rectification ratio (RR) is described as where I (− E ) and I (+ E ) are the measured current values at a defined negative and positive potential, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…2−8 Another more recent nanopore sensing platform is ionic current rectifying (ICR) nanopores. 9 Nanopores with a charged surface and an asymmetry, which can be either an asymmetric geometry (such as a conical nanopore) or asymmetric surface charge distribution, have a non-Ohmic current−voltage curve, where the current measured at one potential is not the same as the current measured at the equal but opposite potential. 10−12 Such a current−voltage curve is said to be rectified, and the rectification ratio (RR) is described as…”

Section: ■ Introductionmentioning

confidence: 99%

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Effect of Electrolyte Concentration and Pore Size on Ion Current Rectification Inversion

et al. 2022

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A thorough understanding of nanoscale transport properties is vital for the development and optimization of nanopore sensors. The thickness of the electrical double layers (EDLs) at the internal walls of a nanopore, as well as the dimensions of the nanopore itself, plays a crucial role in determining transport properties. Herein, we demonstrate the effect of the electrolyte concentration, which is inversely proportional to the EDL thickness, and the effect of pore size, which controls the extent of the electrical double layer overlap, on the ion current rectification phenomenon observed for conical nanopores. Experimental and numerical results showed that as the electrolyte concentration is decreased, the rectification ratio reaches a maximum, then decreases, and eventually inverts below unity. We also show that as the pore size is decreased, the rectification maximum and the inversion take place at higher electrolyte concentrations. Numerical investigations revealed that both phenomena occur due to the shifting of ion enrichment distributions within the nanopore as the electrolyte concentration or the pore size is varied.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Effect of Electrolyte Concentration and Pore Size on Ion Current Rectification Inversion

et al. 2022

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“…In recent decades, unique transport phenomena due to the presence of asymmetric EDL distribution in asymmetrically shaped nanofluidic structures have received considerable research interest [ 26 , 27 , 28 , 29 , 30 ]. Asymmetric nanofluidic structures have been proposed, including polymer nanopores, silicon nanopores, mica nanopores, gold nanotubes, glass nanocapillaries, and glass nanofunnels [ 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

“…Conversely, when the negative voltage bias is applied on the tip side, the negatively charged conical nanopore exhibits a lower ionic current and conductance due to the occurrence of ion depletion inside the nanopore. Furthermore, the ICR phenomenon was used to develop a nanofluidic diode [ 33 ] that has been widely applied in biochemical sensing [ 29 , 30 , 34 ]. Regarding the fundamental studies of the ICR phenomenon, Hsu et al recently showed that EOF, the type of salt, salt concentration, and cone angle all influence the ICR in conical nanopores [ 35 , 36 ].…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Electrokinetic Energy Conversion in Slip Conical Nanopores

Chang

2022

Nanomaterials

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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.

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“…Then, we will consider the protein sensing regarding the technique of detection: the resistive pulse [48,49] and ionic diodes [50,51]. For each strategy, we will discuss their limit and the future to improve the nanopore resolution and accuracy.…”

Section: Introductionmentioning

confidence: 99%