Polyaniline for Improved Blue Energy Harvesting: Highly Rectifying Nanofluidic Diodes Operating in Hypersaline Conditions via One-Step Functionalization

Bioinspired solid-state nanochannels for molecular analysis

The acute sensory behaviour in living organisms relies on the highly efficient transport behaviour of ions in biological nanochannels, which has inspired the design and applications of artificial solid-state nanochannels in the field of sensitive analysis. The application of nanochannels for analysis is now widely investigated, and a variety of sensors have been developed. By coupling reliable nanochannel fabrication techniques with a multitude of surface modification strategies, novel sensors with customized sensing capabilities are generated by the integration of recognition elements and nanochannels. The altered physicochemical properties of these solid-state nanochannel sensors will be manifested by steady-state currents when they are affected by the target analyte. In this mini-review, we focus on emerging solid-state nanochannels based on different fabrication processes such as electron-beam etching, anodic oxidation, ion track etching, and self-assembly. Also, modifications of recognition elements are discussed, including nucleic acids, proteins, small molecules, and responsive materials. The key factors of ion transport behaviour during detection are also reviewed, including surface charge, channel size, and wettability. The applications of these bioinspired nanochannels in the exploration of analysis of small molecules (gas molecules, drug molecules and biological molecules) are concisely presented. Furthermore, we discuss the future developments and challenges.

Unlocking Nanoprecipitation: A Pathway to High Reversibility in Nanofluidic Memristors

Solid-state nanochannels have emerged as a promising platform for the development of ionic circuit components with analog properties to their traditional electronic counterparts. In the last years, nanofluidic devices with memristive properties have attracted special interest due to their applicability in, for example, the construction of brain-like computing systems. In this work, an asymmetric track-etched nanofluidic channel with memory-enhanced ion transport is reported. The results illustrate that the formation of nanoprecipitates on the channel walls induces memory effects in ion transport, leading to characteristic hysteresis loops in the current-voltage curves, a hallmark of memristive behavior. Notably, these memristive properties are achievable with a straightforward experimental setup that combines an aqueous solvent and a relatively low-soluble inorganic salt. The various conductance states can be rapidly and reversibly tuned over prolonged time scales. Furthermore, under appropriate measurement conditions, the nanofluidic device can alternate between different iontronic regimes and states, encompassing ion current rectification, ON-OFF states, and memristor-like behavior. These findings provide insights into the design and optimization of nanofluidic devices for bioinspired ionic circuit components.

Manipulating Ion Transport Regimes in Nanomembranes via a "Pore-in-Pore" Approach Enabled by the Synergy of Metal-Organic Frameworks and Solid-State Nanochannels

Solid-state nanochannels (SSNs) have emerged as promising platforms for controlling ionic transport at the nanoscale. SSNs are highly versatile, and this feature can be enhanced through their combination with porous materials such as Metal-Organic Frameworks (MOF). By selection of specific building blocks and experimental conditions, different MOF architectures can be obtained, and this can influence the ionic transport properties through the nanochannel. Herein, we study the effects of confined synthesis of Zr-based UiO-66 MOF on the ion transport properties of single bullet-shaped poly(ethylene terephthalate) (PET) nanochannels. We have found that emerging textural properties from the MOF phase play a determinant role in controlling ionic transport through the nanochannel. We demonstrate that a transition from ion current saturation regimes to diode-like regimes can be obtained by employing different synthetic approaches, namely, counterdiffusion synthesis, where MOF precursors are kept separate and forced to diffuse through the nanochannel, and one-pot synthesis, where both precursors are placed at both ends of the channel. Also, by considering the dependence of the charge state of the UiO-66 MOF on the protonation degree, pH changes offered a mechanism to tune the iontronic output (and selectivity) among different regimes, including anion-driven rectification, cation-driven rectification, ion current saturation, and ohmic behavior. Furthermore, Poisson-Nernst-Planck (PNP) simulations were employed to rationalize the different iontronic outputs observed experimentally for membranes modified by different methods. Our results demonstrate a straightforward tool to synthesize MOF-based SSN membranes with tunable ion transport regimes.

Conformational transitions in redissolved silk fibroin films and application for printable self-powered multistate resistive memory biomaterials

3D printing of water stable proteins with elastic properties offers a broad range of applications including self-powered biomedical devices driven by piezoelectric biomaterials. Here, we present a study on water-soluble silk fibroin (SF) films. These films were prepared by mixing degummed silk fibers and calcium chloride (CaCl2) in formic acid, resulting in a silk I-like conformation, which was then converted into silk II by redissolving in phosphate buffer (PBS). Circular dichroism, Raman and infrared (IR) spectroscopies were used to investigate the transitions of secondary structure in silk I and silk II as the pH of the solvent and the sonication time were changed. We showed that a solvent with low pH (e.g. 4) maintains the silk I β-turn structure; in contrast solvent with higher pH (e.g. 7.4) promotes β-sheet features of silk II. Ultrasonic treatment facilitates the transition to water stable silk II only for the SF redissolved in PBS. SF from pH 7.4 solution has been printed using extrusion-based 3D printing. A self-powered memristor was realized, comprising an SF-based electric generator and an SF 3D-printed memristive unit connected in series. By exploiting the piezoelectric properties of silk II with higher β-sheet content and Ca2+ ion transport phenomena, the application of an input voltage driven by a SF generator to SF 3D printed holey structures induces a variation from an initial low resistance state (LRS) to a high resistance state (HRS) that recovers in a few minutes, mimicking the transient memory, also known as short-term memory. Thanks to this holistic approach, these findings can contribute to the development of self-powered neuromorphic networks based on biomaterials with memory capabilities.

Organic iontronic memristors for artificial synapses and bionic neuromorphic computing

To tackle the current crisis of Moore's law, a sophisticated strategy entails the development of multistable memristors, bionic artificial synapses, logic circuits and brain-inspired neuromorphic computing. In comparison with conventional electronic systems, iontronic memristors offer greater potential for the manifestation of artificial intelligence and brain-machine interaction. Organic iontronic memristive materials (OIMs), which possess an organic backbone and exhibit stoichiometric ionic states, have emerged as pivotal contenders for the realization of high-performance bionic iontronic memristors. In this review, a comprehensive analysis of the progress and prospects of OIMs is presented, encompassing their inherent advantages, diverse types, synthesis methodologies, and wide-ranging applications in memristive devices. Predictably, the field of OIMs, as a rapidly developing research subject, presents an exciting opportunity for the development of highly efficient neuro-iontronic systems in areas such as in-sensor computing devices, artificial synapses, and human perception.

Asymmetric Nanoporous Alumina Membranes for Nanofluidic Osmotic Energy Conversion

The potential of harnessing osmotic energy from the interaction between seawater and river water has been recognized as a promising, eco-friendly, renewable, and sustainable source of power. The reverse electrodialysis (RED) technology has gained significant interest for its ability to generate electricity by combining concentrated and diluted streams with different levels of salinity. Nanofluidic membranes with tailored ion transport dynamics enable efficient harvesting of renewable osmotic energy. In this regard, anodic aluminum oxide (AAO) membranes with abundant nanochannels provide a cost-effective nanofluidic platform to obtain structures with a high density of ordered pores. AAO can be utilized in constructing asymmetric composite membranes with enhanced ion flux and selectivity to improve output power generation. In this review, we first present the fundamental structure and properties of AAO, followed by summarizing the fabrication techniques for asymmetric membranes using AAO and other nanostructured materials. Subsequently, we discuss the materials employed in constructing asymmetric structures incorporating AAO while emphasizing how material selection and design can resist and promote efficient energy conversion. Finally, we provide an outlook on future applications and address the challenges that need to be overcome for successful osmotic energy conversion.

Robust Cellulose Nanocrystal-Based Self-Assembled Composite Membranes Doped with Polyvinyl Alcohol and Graphene Oxide for Osmotic Energy Harvesting

Osmotic energy from the salinity gradients represents a promising energy resource with stable and sustainable characteristics. Nanofluidic membranes can be considered as powerful alternatives to the traditional low-performance ion exchange membrane to achieve high-efficiency osmotic energy harvesting. However, the development of a highly efficient and easily scalable core membrane component from low-cost raw materials remains challenging. Here, a composite membrane based on the self-assembly of cellulose nanocrystals (CNCs) with polyvinyl alcohol (PVA) and graphene oxide (GO) nanoflakes as additives is developed to provide a solution. The introduction of soft PVA polymer significantly improves the mechanical strength and water stability of the composite membrane by forming a nacre-like structure. Benefiting from the abundant negative charges of CNC nanorods and GO nanoflakes and the generated network nanochannels, the composite membrane demonstrates a good cation-selective transport capacity, thus contributing to an optimal osmotic energy conversion of 6.5 W m-2 under a 100-fold salinity gradient and an exemplary stability throughout 25 consecutive days of operation. This work provides an option for the development of nanofluidic membranes that can be easily produced on a large scale from well-resourced and sustainable biomass materials for high-efficiency osmotic energy conversion.

Confined Ionic-Liquid-Mediated Cation Diffusion through Layered Membranes for High-Performance Osmotic Energy Conversion

Ion-selective membranes act as the core components in osmotic energy harvesting, but remain with deficiencies such as low ion selectivity and a tendency to swell. 2D nanofluidic membranes as competitive candidates are still subjected to limited mass transport brought by insufficient wetting and poor stability in water. Here, an ionic-liquid-infused graphene oxide (GO@IL) membrane with ultrafast ion transport ability is reported, and how the confined ionic liquid mediates selective cation diffusion is revealed. The infusion of ionic liquids endows the 2D membrane with excellent mechanical strength, anti-swelling properties, and good stability in aqueous electrolytes. Importantly, immiscible ionic liquids also provide a medium, allowing partial dehydration for ultrafast ion transport. Through molecular dynamics simulation and finite element modeling, that GO nanosheets induce ionic liquids to rearrange, bringing in additional space charges, which can be coupled with GO synergistically, is proved. By mixing 0.5/0.01 m NaCl solution, the power density can achieve a record value of ≈6.7 W m^-2 , outperforming state-of-art GO-based membranes. This work opens up a new route for boosting nanofluidic energy conversion because of the diversity of the ILs and 2D materials.

Temperature dependent characteristics of flexible p-PANI/n-ZnO based hybrid heterojunction diode

This study aims to develop and characterize a flexible p-PANI/n-ZnO heterojunction diode developed from a combination of electrochemical and sputtering technique. Investigation of structural properties and morphology of the thin films has been done from XRD and SEM analysis. To study the temperature effect on the electrical properties of the diode, current-voltage-temperature (I-V-T) measurements were done for the temperature range 25-300 K. Applying the ideal thermionic emission theory, various diode parameters like reverse saturation current, quality factor, series resistance and barrier height were computed utilizing the semilogarithmic plot ofI-Vcurve and Cheungs' method. Barrier height, reverse saturation current and quality factor calculated from ln(I)versusVcurve were observed to vary from 0.0627-0.725 eV, 0.236-98.8 nA and 54.43-3.29 respectively over the temperature range 25-300 K. It has been found that the series resistance falls with a rise in temperature. The barrier height, series resistance and ideality factor were observed to vary from 0.0628-0.692 eV, 15 900-46.8 Kohm and 41.88-2.27 respectively for the temperature range 25-300 K. The activation energy estimated from Arrhenius plot was observed to be 14.51 meV. Additionally, the fabricated PANI/ZnO diode was mechanically robust that can be bent without affecting its performance.

Membranes for Osmotic Power Generation by Reverse Electrodialysis

In recent years, the utilization of the selective ion transport through porous membranes for osmotic power generation (blue energy) has received a lot of attention. The principal of power generation using the porous membranes is same as that of conventional reverse electrodialysis (RED), but nonporous ion exchange membranes are conventionally used for RED. The ion transport mechanisms through the porous and nonporous membranes are considerably different. Unlike the conventional nonporous membranes, the ion transport through the porous membranes is largely dictated by the principles of nanofluidics. This owes to the fact that the osmotic power generation via selective ion transport through porous membranes is often referred to as nanofluidic reverse electrodialysis (NRED) or nanopore-based power generation (NPG). While RED using nonporous membranes has already been implemented on a pilot-plant scale, the progress of NRED/NPG has so far been limited in the development of small-scale, novel, porous membrane materials. The aim of this review is to provide an overview of the membrane design concepts of nanofluidic porous membranes for NPG/NRED. A brief description of material design concepts of conventional nonporous membranes for RED is provided as well.

Electrochemically addressed FET-like nanofluidic channels with dynamic ion-transport regimes

Nanofluidic channels in which the ionic transport can be modulated by the application of an external voltage to the nanochannel walls have been described as nanofluidic field effect transistors (nFETs) because of their analogy with electrolyte-gated field effect transistors. The creation of nFETs is attracting increasing attention due to the possibility of controlling ion transport by using an external voltage as a non-invasive stimulus. In this work, we show that it is possible to extend the actuation range of nFETs by using the supporting electrolyte as a "chemical effector". For this aim, a gold-coated poly(ethylene terephthalate) (PET) membrane was modified with electroactive poly-o-aminophenol. By exploiting the interaction between the electroactive poly-o-aminophenol and the ions in the electrolyte solution, the magnitude and surface charge of the nanochannels were fine-tuned. In this way, by setting the electrolyte nature it has been possible to set different ion transport regimes, i.e.: cation-selective or anion-selective ion transport, whereas the rectification efficiency of the ionic transport was controlled by the gate voltage applied to the electroactive polymer layer. Remarkably, under both regimes, the platform displays a reversible and rapid response. We believe that this strategy to preset the actuation range of nFETs by using the supporting electrolyte as a chemical effector can be extended to other devices, thus offering new opportunities for the development of stimulus-responsive solid-state nanochannels.

Influences of Divalent Ions in Natural Seawater/River Water on Nanofluidic Osmotic Energy Generation

Besides the dominant NaCl, natural seawater/river water contains trace multivalent ions, which can provide effective screening of surface charges. Here, in both negatively and positively charged nanopores, influences from divalent ions as counterions and co-ions have been investigated with respect to the performance of osmotic energy conversion (OEC) under natural salt gradients. As counterions, trace Ca²⁺ ions can suppress the electric power and conversion efficiency significantly. The reduced OEC performance is due to the bivalence and low diffusion coefficient of Ca²⁺ ions instead of the uphill transport of divalent ions discovered in the previous work. Effectively screened charged surfaces by Ca²⁺ ions induce an enhanced diffusion of Cl^- ions which simultaneously decreases the net ion penetration and ionic selectivity of the nanopore. As co-ions, Ca²⁺ ions have weak effects on the OEC performance. The promotion from charged exterior surfaces in OEC processes for ultrashort nanopores is also studied, with an effective region of ∼200 nm in width beyond pore boundaries independent of the presence of Ca²⁺ ions. Our results shed light on the physical details of the nanofluidic OEC process under natural seawater/river water conditions, which can provide a useful guide for high-performance osmotic energy harvesting.

A Euryhaline-Fish-Inspired Salinity Self-Adaptive Nanofluidic Diode Leads to High-Performance Blue Energy Harvesters

The adaptability to wide salinities remains a big challenge for artificial nanofluidic systems, which plays a vital role in water-energy nexus science. Here, inspired by euryhaline fish, sandwich-structured nanochannel systems are constructed to realize salinity self-adaptive nanofluidic diodes, which lead to high-performance salinity-gradient power generators with low internal resistance. Adaptive to changing salinity, the pore morphology of one side of the nanochannel system switches from a 1D straight nanochannel (45 nm) to 3D network pores (1.9 nm pore size and ≈10¹³ pore density), along with three orders of magnitude change for charge density. Thus, the abundant surface charges and narrow pores render the membrane-based osmotic power generator with power density up to 26.22 Wm^-2 . The salinity-adaptive membrane solves the surface charge-shielding problem caused by abundant mobile ions in high salinity and increases the overlapping degree of the electric double layer. The dynamic adaption process of the membrane to the hypersaline environment endows it with good salt endurance and stability. New routes for designing nanofluidic devices functionally adaptable to different salinities and building power generators with excellent salt endurance are demonstrated.

High-Performance Osmotic Power Generators Based on the 1D/2D Hybrid Nanochannel System

Extracting clean energy by converting the salinity gradient between river and sea into energy is an effective way to reduce the global pollution and carbon emissions. Reverse electrodialysis (RED) is of great importance to realize the energy conversion assisting the ion-selective membrane. However, its higher ion resistance and lower conversion efficiency results in the undesirable power conversion performance. Here, we demonstrate a 1D/2D hybrid nanochannel system to achieve high osmotic energy conversion and output power. This heterogeneous structure is composed of two structures, in which the subnanometer nanochannels in graphene oxide membrane (GOM) can serve as a selective layer and reduce the ion diffusion energy barrier, while the nanochannel in the polymer can introduce asymmetry to enhance ionic rectification and conversion efficiency. This heterogeneous membrane exhibits excellent cation selectivity and enhanced ionic current rectification (ICR) performance. The application of the GOM/PET hybrid nanochannel system in osmotic energy harvesting is evaluated, and the output power can reach up to 118.2 pW with the energy conversion efficiency of 40.3%. Theoretical calculation indicates that the 1D/2D hybrid system can effectively take the advantage of excellent cation selectivity of 2D lamellar nanochannels to improve its RED performance significantly.

Light-Enhanced Osmotic Energy Harvester Using Photoactive Porphyrin Metal-Organic Framework Membranes

High ion selectivity and permeability, as two contradictory aspects for the membrane design, highly hamper the development of osmotic energy harvesting technologies. Metal-organic frameworks (MOFs) with ultra-small and high-density pores and functional surface groups show great promise in tackling these problems. Here, we propose a facile and mild cathodic deposition method to directly prepare crack-free porphyrin MOF membranes on a porous anodic aluminum oxide for osmotic energy harvesting. The abundant carboxyl groups of the functionalized porphyrin ligands together with the nanoporous structure endows the MOF membrane with high cation selectivity and ion permeability, thus a large output power density of 6.26 W m^-2 is achieved. The photoactive porphyrin ligands further lead to an improvement of the power density to 7.74 W m^-2 upon light irradiation. This work provides a promising strategy for the design of high-performance osmotic energy harvesting systems.

Ultrafast rectifying counter-directional transport of proton and metal ions in metal-organic framework-based nanochannels

Bioinspired control of ion transport at the subnanoscale has become a major focus in the fields of nanofluidics and membrane separation. It is fundamentally important to achieve rectifying ion-specific transport in artificial ion channels, but it remains a challenge. Here, we report a previously unidentified metal-organic framework nanochannel (MOF NC) nanofluidic system to achieve unidirectional ultrafast counter-directional transport of alkaline metal ions and proton. This highly effective ion-specific rectifying transport behavior is attributed to two distinct mechanisms for metal ions and proton, elucidated by theoretical simulations. Notably, the MOF NC exhibits ultrafast proton conduction stemming from ultrahigh proton mobility, i.e., 11.3 × 10^-7 m² /V·s, and low energy barrier of 0.075 eV in MIL-53-COOH subnanochannels. Furthermore, the MOF NC shows excellent osmotic power-harvesting performance in reverse electrodialysis. This work expects to inspire further research into multifunctional biomimetic ion channels for advanced nanofluidics, biomimetics, and separation applications.

Nanofluidic osmotic power generators - advanced nanoporous membranes and nanochannels for blue energy harvesting

The increase of energy demand added to the concern for environmental pollution linked to energy generation based on the combustion of fossil fuels has motivated the study and development of new sustainable ways for energy harvesting. Among the different alternatives, the opportunity to generate energy by exploiting the osmotic pressure difference between water sources of different salinities has attracted considerable attention. It is well-known that this objective can be accomplished by employing ion-selective dense membranes. However, so far, the current state of this technology has shown limited performance which hinders its real application. In this context, advanced nanostructured membranes (nanoporous membranes) with high ion flux and selectivity enabling the enhancement of the output power are perceived as a promising strategy to overcome the existing barriers in this technology. While the utilization of nanoporous membranes for osmotic power generation is a relatively new field and therefore, its application for large-scale production is still uncertain, there have been major developments at the laboratory scale in recent years that demonstrate its huge potential. In this review, we introduce a comprehensive analysis of the main fundamental concepts behind osmotic energy generation and how the utilization of nanoporous membranes with tailored ion transport can be a key to the development of high-efficiency blue energy harvesting systems. Also, the document discusses experimental issues related to the different ways to fabricate this new generation of membranes and the different experimental set-ups for the energy-conversion measurements. We highlight the importance of optimizing the experimental variables through the detailed analysis of the influence on the energy capability of geometrical features related to the nanoporous membranes, surface charge density, concentration gradient, temperature, building block integration, and others. Finally, we summarize some representative studies in up-scaled membranes and discuss the main challenges and perspectives of this emerging field.

Distinct Chemistries Explain Decoupling of Slip and Wettability in Atomically Smooth Aqueous Interfaces

Despite essentially identical crystallography and equilibrium structuring of water, nanoscopic channels composed of hexagonal boron nitride and graphite exhibit an order-of-magnitude difference in fluid slip. We investigate this difference using molecular dynamics simulations, demonstrating that its origin is in the distinct chemistries of the two materials. In particular, the presence of polar bonds in hexagonal boron nitride, absent in graphite, leads to Coulombic interactions between the polar water molecules and the wall. We demonstrate that this interaction is manifested in a large typical lateral force experienced by a layer of oriented hydrogen atoms in the vicinity of the wall, leading to the enhanced friction in hexagonal boron nitride. The fluid adhesion to the wall is dominated by dispersive forces in both materials, leading to similar wettabilities. Our results rationalize recent observations that the difference in frictional characteristics of graphite and hexagonal boron nitride cannot be explained on the basis of the minor differences in their wettabilities.

"Ion Pool" Structural Ion Storage Device: A New Strategy to Collect Ions by Nanoconfinement Effects

Ion storage structure widely exists in organisms, which is used to harvesting energy in environment and converting it into ion concentration gradient to maintain complex life activities. The construction of ion storage structures relies on isolating the biological body fluids by biofilm systems, which can also be regarded as local ions confinement. Mimicking this ions storage process, an "ion pool" structural ion storage device is proposed in this research by artificial ion nanochannels, which can transform the electric power into ion concentration gradient. It is consisted of micrometer-sized ions reservoir and nanosized ions filters. Ions can be isolated within the "pool" and performed ultrahigh ions enrichment or depletion behavior deviated from bulk. Through numerical simulation by Poisson-Nernst-Planck equations, "ion pool" structural device achieves nearly 20 000 rectification ratio with low surface charge. An "ion pool" structural ions storage device is also constructed with block copolymer and polyethylene terephthalate composite membranes, a super high rectification ratio of 3184.0 is achieved from the experiment, which is the highest reported so far. The ion storage efficiency of the device reaches 14.90%, which is an order of magnitude better than non-"ion pool" structural nanofluid devices.

Borate-driven ionic rectifiers based on sugar-bearing single nanochannels

Recently, much scientific effort has been centered on the control of the ionic transport properties of solid state nanochannels and the rational design and integration of chemical systems to induce changes in the ionic transport by means of interactions with selected target molecules. Here, we report the fabrication of a novel nanofluidic device based on solid-state nanochannels, which combines silane chemistry with both track-etched and atomic layer deposition (ALD) technologies. Nanodevice construction involves the coating of bullet-shaped single-pore nanochannels with silica (SiO₂) by ALD and subsequent surface modification by reaction between silanol groups exposed on pore walls and N-(3-triethoxysilylpropyl)-gluconamide, in order to create a gluconamide-decorated nanochannel surface. The formation of a boroester derivative resulting from the selective reaction of borate with the appended saccharides leads to important changes in the surface charge density and, concomitantly, in the iontronic properties of the nanochannel. Furthermore, we propose a binding model to rationalize the specific interaction saccharide-borate in the surface. Besides, this unique nanodevice exhibits a highly selective and reversible response towards borate/fructose exposure. On the basis of the surface charge variation resulting from borate binding, the nanochannel can reversibly switch between "ON" and "OFF" states in the presence of borate and fructose, respectively. In addition, this work describes the first report of the functionalization of PET/SiO₂ nanochannels by the ALD technique. We believe that this work provides a promising framework for the development of new nanochannel-based platforms suitable for multiple applications, such as water quality monitoring or directed molecular transport and separation.

Engineering a Smart Nanofluidic Sensor for High-Performance Peroxynitrite Sensing through a Spirocyclic Ring Open/Close Reaction Strategy

Peroxynitrite (ONOO^-) is an important reactive oxygen/nitrogen species that participates in a range of physiological and pathological processes by modulating ion flux through biological channels. Inspired by a ONOO^--regulated K⁺ channel in vivo, herein, we describe the construction of a smart ONOO^--driven nanosensor using a spirocyclic ring open/close reaction approach. The prepared nanosensor possessed a prominent ONOO^- selectivity and sensitivity and rapid response (∼90 s) owing to the specific reaction between ONOO^- and ligands on the nanosensor surface with a high ion rectification ratio (∼10) and ion gating ratio (∼4). Moreover, this nanosensor system also exhibits excellent stability and recyclability. Thus, these results will provide a new direction for the design of nanochannel-based sensors for future practical and biological applications.