Solid-State Ionic Diodes Demonstrated in Conical Nanopores

Plett, Timothy S.; Cai, Wenjia; Thai, Mya Le; Vlassiouk, Ivan; Penner, Reginald M.; Siwy, Zuzanna S.

doi:10.1021/acs.jpcc.7b00258

Cited by 37 publications

(39 citation statements)

References 59 publications

(108 reference statements)

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“…Solid‐state nanochannels/nanopores are adopted widely to simulate the ionic transport in biological systems, and various applications proposed, recently. The latter includes, for example, ionic gates [1, 2], nanofluidic diodes [3–6], energy conversion [7, 8], and filtration/desalination [9, 10]. The phenomena and mechanisms associated with nanochannels/nanopores rest mainly on the nonuniform distribution of ion species and the overlapping of the electric double layer (EDL) in their interior [11, 12].…”

Section: Introductionmentioning

confidence: 99%

“…ICR, an asymmetric current‐voltage behavior when the potential polarity is switched, has been identified in several logic nanofluidic devices [1–6]. Through many experimental and theoretical studies conducted in the last decades, it has been concluded that the ICR phenomenon of nanochannels/nanopores can be attributed to their asymmetric characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Ion current rectification behavior of a nanochannel having nonuniform cross‐section

2020

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Ion current rectification behavior of a nanochannel having nonuniform cross-sectionDue to its versatile applications in biotechnology, ion current rectification (ICR), which arises from the asymmetric nature of the ion transport in a nanochannel, has drawn much attention, recently. Here, the ICR behavior of a pH-regulated nanochannel comprising two series connected cylindrical nanochannels of different radii is examined theoretically, focusing on the influences of the radii ratio, the length ratio, the bulk concentration, and the solution pH. The results of numerical simulation reveal that the rectification factor exhibits a local maximum with respect to both the radii ratio and the length ratio. The values of the radii ratio and the length ratio at which the local maximum in the rectification factor occur depend upon the level of the bulk salt concentration. The rectification factor also shows a local maximum as the solution pH varies. Among the factors examined, the solution pH influences the ICR behavior of the nanochannel most significantly.Abbreviations: AAO, anodic aluminum oxide; EDL, electric double layer; ICR, ion current rectification; IEP, isoelectric point been concluded that the ICR phenomenon of nanochannels/nanopores can be attributed to their asymmetric characteristics. These include, for instance, geometry [20][21][22][23][24][25][26][27][28], surface charge [29, 30], chemical composition [31, 32], wettability [33], and external applied fields such as pH gradient [34], electrolyte concentration gradient [35], and pressure gradient [36]. Among these, geometry-induced ICR draws much attention because the associated nanochannel fabrication methods are convenient and controllable. These include, for example, track-etching [37], focused ion beam sculpting [38], and electron-beam lithography [39]. Through these methods, various types of nanochannels have been fabricated such as cylindrical [27], conical [22], hourglass-shaped [26], cigar-shaped [20], bullet-shaped [25], dumbbell-shaped [21], and funnelshaped nanochannels [23]. The ICR behavior of an asymmetric nanochannel can be influenced by factors including ionic species [40], ion concentration [35, 41], applied electric potential [40], pH [42, 43], temperature [44], and nanochannel length and its opening radii [24,45,46]. The cone angle [24] and the ratio of cylindrical segment/conical segment [23] are important to conical and funnel-shaped nanochannels, respectively.Previous studies regarding asymmetric nanochannel focused mainly on polymeric material such as polycarbonate Color online: See article online to view Figs. 1-8 in color.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ion current rectification behavior of a nanochannel having nonuniform cross‐section

2020

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“…Today, the ionic diode field is dominatd by nanochannel [12], nanocone [13,14], and nanopore [15,16] devices that mimic much more closely the biological ion channels located in membranes [17]. A wide range of nano-architectures [18,19] and applications [20] has been proposed, pHswitchable devices have been developed [21], and a perspectives review has appeared with focus on stimuli response "iontronics" [22].…”

Section: Introductionmentioning

confidence: 99%

Potassium cation induced ionic diode blocking for a polymer of intrinsic microporosity | nafion “heterojunction” on a microhole substrate

Putra

Carta

Malpass‐Evans

et al. 2017

Electrochimica Acta

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Heterojunction" ionic diodes based on a Nafion cation conductor and a polymer of intrinsic microporosity (PIM) interfaced at a 6 m thickness polyethylene-terephthalate (PET) film with 20 m diameter microhole exhibit rectification effects in cation (K +) flux. When combined with the precipitation reaction of potassium cations with perchlorate anions to give insoluble KClO4 (solubility product ca. 1.05 × 10-2 M 2 at 25 o C) at the PIM | Nafion interface, inversion of the rectification/diode effect occurs and the formerly "open" state changes into a "closed" state due to blocking of ion flow. The localised interfacial precipitation reaction is due to up to three orders of magnitude accumulation of K + at the PIM | Nafion interface and shown to be fast and reversible. The effects of K + /ClO4concentration and of Na + interference are considered. The blocking process within the heterojunction ionic diode is suggested to be dynamic/fast and potentially useful as a diode sensor mechanism based on solubility product dependent precipitation.

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“…In most studies, inorganic salts (e.g., KCl and NaCl) in aqueous solutions have been used. Siwy and co-workers have considered the case of ionic liquids, aprotic solvents, and solid-state electrolytes [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Tetraalkylammonium Cations Conduction through a Single Nanofluidic Diode: Experimental and Theoretical Studies

Ali

Ramı́rez

Nasir

et al. 2017

Electrochimica Acta

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We describe experimentally and theoretically the concentration-dependent conduction of tetraalkylammonium (TAA +) cations through a nanofluidic diode fabricated in a polymer membrane via asymmetric track-etching techniques. This single-pore membrane exhibits current rectification characteristics because of the ionized carboxylate groups on the pore surface. We use aqueous solutions of potassium (K +), ammonium (A +), tetramethylammonium (TMA +), tetraethylammonium (TEA +), and tetrabutylammonium (TBA +) ions with concentrations ranging from 50 to 500 mM under acidic (pH 3.5) and physiological (pH 6.5) conditions. Compared with the K + and A + ions, the TMA + , TEA + , and TBA + ions show relatively low rectified ion currents because the cation hydrophobicity increases with the alkyl chain. At low concentrations and acidic conditions, an inversion in the current rectification characteristics is observed, which is attributed to the adsorption of the organic cations on the pore surfaces. The experimental results can be analyzed in terms of the Poisson-Nernst-Planck equations and the geometrical and electrical single pore characteristics for the different ions, pH values, and salt concentrations employed. This theoretical approach is qualitative and could be extended further to include a selfconsistent theoretical treatment of the ionic adsorption and surface charge equilibria.

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Solid-State Ionic Diodes Demonstrated in Conical Nanopores

Cited by 37 publications

References 59 publications

Ion current rectification behavior of a nanochannel having nonuniform cross‐section

Ion current rectification behavior of a nanochannel having nonuniform cross‐section

Potassium cation induced ionic diode blocking for a polymer of intrinsic microporosity | nafion “heterojunction” on a microhole substrate

Tetraalkylammonium Cations Conduction through a Single Nanofluidic Diode: Experimental and Theoretical Studies

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