Current rectification by nanoparticles in bipolar nanopores

Córdoba, Andrés; de, Joan Manuel Montes; Dhanasekaran, Johnson; Darling, Seth B.; Pablo, Juan

doi:10.1039/d2me00187j

Cited by 4 publications

(12 citation statements)

References 39 publications

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“…This phenomenon is not observed in the +2 V case, therefore, it results in a very large rectification ratio for the case of an electrolyte with NaCl and charged nanoparticles when ϵ = 78.9. Note that we have previously shown that at the concentration of nanoparticles that we use here (0.7 mM), their direct contribution to the electric current is always less than 1% . The increase in current rectification caused by the addition of nanoparticles is related to their effect on the charge distribution inside the channel, as discussed in more detail below.…”

Section: Resultsmentioning

confidence: 67%

“…From a practical perspective, we consider the presence of nanoparticles because they might already be present in the water bodies used in membrane-based RED processes for energy generation. Moreover, we have observed in our previous work that low concentrations of nanoparticles can, under certain conditions, increase current rectification in bipolar nanopores . Here, we report simulations at two levels of description.…”

Section: Introductionmentioning

confidence: 90%

“…Other works have focused on comparisons of the predictions from continuum models, such as PNP theory and stochastic simulations of ionic conduction in charged pores. − Although both levels of detail provide comparable descriptions of the ionic transport in bulk solutions, significant differences were observed when the relevant length scales of the system started to overlap. In particular, large discrepancies were found between the continuum and discrete simulations regarding the distribution of ions in the systems (and the corresponding conductivity) when the radius of the pores is comparable to the Debye length.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, we have observed in our previous work that low concentrations of nanoparticles can, under certain conditions, increase current rectification in bipolar nanopores. 20 Here, we report simulations at two levels of description. At the more detailed level, we rely on all-atom explicit water simulations, which do not require the prescription of collective parameters such as the viscosity and dielectric constant of the electrolyte solvent beyond what is predicted by the force field.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Dielectric Constant on the Ionic Current Rectification of Bipolar Nanopores

Córdoba,

Montes de Oca,

Darling

et al. 2024

ACS Nano

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In this paper, we investigate how the dielectric constant, ϵ, of an electrolyte solvent influences the current rectification characteristics of bipolar nanopores. It is well recognized that bipolar nanopores with two oppositely charged regions rectify current when exposed to an alternating electric potential difference. Here, we consider dilute electrolytes with NaCl only and with a mixture of NaCl and charged nanoparticles. These systems are studied using two levels of description, all-atom explicit water molecular dynamics (MD) simulations and coarse-grained implicit solvent MD simulations.The charge density and electric potential profiles and current− voltage relationship predicted by the implicit solvent simulations with ϵ = 11.3 show good agreement with the predictions from the explicit water simulations. Under nonequilibrium conditions, the predictions of the implicit solvent simulations with a dielectric constant closer to the one of bulk water are significantly different from the predictions obtained with the explicit water model. These findings are closely aligned with experimental data on the dielectric constant of water when confined to nanometric spaces, which suggests that ϵ decreases significantly compared to its value in the bulk. Moreover, the largest electric current rectification is observed in systems containing nanoparticles when ϵ = 78.8. Using enhanced sampling, we have shown that this larger rectification arises from the presence of a significantly deeper minimum in the free energy of the system with a larger ϵ, and when a negative voltage bias is applied. Since implicit solvent models and mean-field continuum theories are often used to design Janus membranes based on bipolar nanopores, this work highlights the importance of properly accounting for the effects of confinement on the dielectric constant of the electrolyte solvent. The results presented here indicate that the dielectric constant in implicit solvent simulations may be used as an adjustable parameter to approximately account for the effects of nanometric confinement on aqueous electrolyte solvents.

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Section: Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of the Dielectric Constant on the Ionic Current Rectification of Bipolar Nanopores

Córdoba,

Montes de Oca,

Darling

et al. 2024

ACS Nano

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“…[15] and was later modified by replacing the UP channels with conical channels carrying a BP inhomogeneous surface charge [39], positive at the base and negative at the tip. BP fluidic channels and (Janus) membranes have long drawn great interest as current rectifiers [42][43][44][45][46][47] for applications in e.g. sensing [47] and osmotic energy conversion [47][48][49].…”

Section: Iontronic Circuit and Bp Channelsmentioning

confidence: 99%

Advanced iontronic spiking modes with multiscale diffusive dynamics in a fluidic circuit

Kamsma,

Rossing,

Spitoni

et al. 2024

Neuromorph. Comput. Eng.

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Fluidic iontronics is emerging as a distinctive platform for implementing neuromorphic circuits, characterised by its reliance on the same aqueous medium and ionic signal carriers as the brain. Drawing upon recent theoretical advancements in both iontronic spiking circuits and in dynamic conductance of conical ion channels, which form fluidic memristors, we expand the repertoire of proposed neuronal spiking dynamics in iontronic circuits. Through a modelled circuit containing channels that carry a bipolar surface charge, we extract phasic bursting, mixed-mode spiking, tonic bursting, and threshold variability, all with spike voltages and frequencies within the typical range for mammalian neurons. These features are possible due to the strong dependence of the typical conductance memory retention time on the channel length, enabling timescales varying from individual spikes to bursts of multiple spikes within a single circuit. These advanced forms of neuronal-like spiking support the exploration of aqueous iontronics as an interesting platform for neuromorphic circuits.

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Bipolar nanochannels: the effects of an electroosmotic instability. Part 1. Steady-state response

Abu-Rjal,

Green

2024

Flow

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The steady-state current–voltage response of ion-selective systems varies as the number of ion-selective components is varied. For the highly investigated unipolar system, including only one ion-selective component, it has been shown that above a supercritical voltage, an electroosmotic instability is triggered, leading to overlimiting currents. In contrast, the effects of this instability on the current–voltage response of the second most common system of a bipolar system, including two oppositely charged permselective regions, have yet to be reported. Using numerical simulations, we investigate the steady-state electrical response of bipolar systems as we vary the ratio of the charge within the two oppositely charged regions. The responses are divided into those with an internal symmetry related to the surface charge and those without. In contrast to the unipolar systems, bipolar systems with the internal symmetry do not exhibit overlimiting currents and their steady-state response is identical to the convectionless steady-state response. In contrast, the systems without the internal symmetry exhibit much more complicated behaviour. For positive voltages, they have overlimiting currents, while for negative voltages, they do not have overlimiting currents. Our findings contribute to a more profound understanding of the behaviour of the current–voltage response in bipolar systems.

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Current rectification by nanoparticles in bipolar nanopores

Abstract: Bipolar nanochannels comprising two domains of positively and negatively charged walls along the pore axis are known to rectify current when exposed to an electric potential bias. We find that...

Cited by 4 publications

References 39 publications

Influence of the Dielectric Constant on the Ionic Current Rectification of Bipolar Nanopores

Influence of the Dielectric Constant on the Ionic Current Rectification of Bipolar Nanopores

Advanced iontronic spiking modes with multiscale diffusive dynamics in a fluidic circuit

Bipolar nanochannels: the effects of an electroosmotic instability. Part 1. Steady-state response

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