Indium Tin Oxide Electrode Research Articles

Electrochemical nucleation and growth kinetics: insights from single particle scanning electrochemical cell microscopy studies.

The kinetics of particle nucleation and growth are critical to a wide variety of electrochemical systems. While studies carried out at the single particle level are promising for improving our understanding of nucleation and growth processes, conventional analytical frameworks commonly employed in bulk studies may not be appropriate for single particle experiments. Here, we present scanning electrochemical cell microscopy (SECCM) studies of Ag nucleation and growth on carbon and indium tin oxide (ITO) electrodes. Statistical analyses of the data from these experiments reveal significant discrepancies with traditional, quasi-equilibrium kinetic models commonly employed in the analysis of particle nucleation in electrochemical systems. Time-dependent kinetic models are presented capable of appropriately analysing the data generated via SECCM to extract meaningful chemical quantities such as surface energies and kinetic rate constants. These results demonstrate a powerful new approach to the analysis of single particle nucleation and growth data which could be leveraged in differentiating behavior within spatially heterogeneous systems.

Mesoporous Electrodes Enhance the Electrocatalytic Performance of [FeFe]-Hydrogenase.

The metalloenzyme [FeFe]-hydrogenase is of interest to future biotechnologies targeting the production of "green" hydrogen (H2). We recently developed a simple two-step functionalized procedure to immobilize the [FeFe]-hydrogenase from Clostridium pasteurianum ("CpI") on mesoporous indium tin oxide (ITO) electrodes to achieve elevated H2 production with high operational stability, with current densities of 8 mA cm-2. Here, we use a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical quartz crystal microbalance (EQCM) to understand how mesoporous ITO stabilizes and activates CpI for electroenzymatic H2 production. Examination of the topography and morphology of the mesoporous ITO surface revealed a hierarchical morphology containing cavities and well-defined nanoparticle agglomerates. Any potential effect of mesoporosity was investigated by comparing the stability and electroenzymatic activity of CpI on mesoporous 'nanoITO' and planar ITO, where we determined that CpI has a higher turnover frequency and absorbs with greater stability (with respect to electroenzymatic activity over time) to nanoITO surfaces.

Mesoporous Electrodes Enhance the Electrocatalytic Performance of [FeFe]‐Hydrogenase

The metalloenzyme [FeFe]‐hydrogenase is of interest to future biotechnologies targeting the production of “green” hydrogen (H2). We recently developed a simple two‐step functionalized procedure to immobilize the [FeFe]‐hydrogenase from Clostridium pasteurianum (“CpI”) on mesoporous indium tin oxide (ITO) electrodes to achieve elevated H2 production with high operational stability, with current densities of 8 mA cm–2. Here, we use a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical quartz crystal microbalance (EQCM) to understand how mesoporous ITO stabilizes and activates CpI for electroenzymatic H2 production. Examination of the topography and morphology of the mesoporous ITO surface revealed a hierarchical morphology containing cavities and well‐defined nanoparticle agglomerates. Any potential effect of mesoporosity was investigated by comparing the stability and electroenzymatic activity of CpI on mesoporous ‘nanoITO’ and planar ITO, where we determined that CpI has a higher turnover frequency and absorbs with greater stability (with respect to electroenzymatic activity over time) to nanoITO surfaces.

Enhanced electrocatalytic activity by nanoconfinement effects at nanoporous indium tin oxide electrodes

AbstractAmong various strategies to enhance electrocatalytic activity, nanoporous structured electrodes have been widely utilized owing to their improved performance. Along with enlarged electrode surface, modified crystalline facets, and surface defects of nanoporous electrodes, recent studies have reported their unique electrocatalytic characteristics originating from the nanoconfined space, denoted as the nanoconfinement effect. Introducing nanoporous electrodes with controllable thickness made of indium tin oxide, an electrochemically inert material, has provided an optimal platform for analyzing the contribution of nanoporous structures to the catalytic effects. Nevertheless, the scope of reactants that has been studied based on this system so far is mostly limited to ferric/ferrous redox species in sulfate anion environment. Here, using the nanoporous indium tin oxide electrodes, we demonstrate the nanoconfinement effect toward the ferric/ferrous reaction in a different chemical environment that alters its electrokinetic characteristics compared to the previous studies. Furthermore, a complex multi‐electron transfer reaction of oxygen reduction is employed to explore the effects of nanoporous structure toward inner‐sphere reactions. Our work suggests that the nanoconfinement effects can be applied to a wider range of electrochemical reactions taking place in nanoporous electrodes.

Molecularly imprinted electrochemical sensor based on APTES-functionalized indium tin oxide electrode for the determination of sulfadiazine.

Anelectrochemical sensor was developedfor the sensitive and selective detection of sulfadiazine(SDZ), based on a molecularly imprinted polymer (MIP) film formed on an indium tin oxide (ITO) electrode through a self-assembly process. The SDZ-imprinted ITO electrode (SDZ-MIP/APTES-ITO) was prepared through in situ polymerization using sulfadiazine, methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), and 2,2'-azobisisobutyronitrile (AIBN) as the template, functional monomer, cross-linker, and initiator respectively. Before polymerization, the ITO electrode was functionalized with 3-aminopropyltriethoxysilane (APTES) to promote covalent attachment of the polymer to the electrode. After polymerization, the template molecule SDZ was removed to create selective recognition sites, forming the molecularly imprinted polymer electrode (MIP/APTES-ITO), which facilitates sulfadiazine detection. The sensor's performance was evaluated using cyclic and differential pulse voltammetry, demonstrating a linear response in the sulfadiazine concentration range 0.1 to 300μM, with a detection limit of 0.11μM. The MIP-based sensor exhibited goodreproducibility, repeatability, selectivity, and stability in sulfadiazine detection. Its practical applicability was confirmed by the successful quantification of sulfadiazine in spiked milk samples.

Gold–Graphene Quantum Dot Hybrid Nanoparticle for Smart Diagnostics of Prostate Cancer

Prostate cancer is one of the most prevalent cancers afflicting men worldwide, often detected at advanced stages, leading to increased mortality rates. Addressing this challenge, we present an innovative approach employing electrochemical biosensing for early-stage prostate cancer detection. This study used Indium–Tin Oxide (ITO) as a substrate and a deposited gold–graphene quantum dot (Au–GQD) nanohybrid to establish electrochemical sensing platforms for DNA-hybridization assays. A capturing DNA probe, PCA3, was covalently immobilized on the surface of the Au–GQDs and deposited electrochemically onto the ITO electrode surface. The Au–GQDs enabled the capturing of the target PCA3 biomarker probe. The sensor achieved a limit of detection (LoD) of up to 211 fM and presented a linear detection range spanning 1 µM to 100 fM. A rapid 5-min response time was also achieved. The tested shelf life of the pre-immobilized sensor was approximately 19 ± 1 days, with pronounced selectivity for its intended target amidst various interferants. The sensing device has the potential to revolutionize prostate cancer management by facilitating early-stage detection and screening with enhanced treatment efficacy.

Photocurrent-polarity-switching photoelectrochemical and electrochemical dual-mode sensing platform for the highly selective detection of trenbolone

As an emerging contaminant in the environment, trenbolone (TBE) has aroused a global health crisis and caused the huge impact on ecosystem. Its sensitive detection is critical to safeguard human health and ecosystem. Herein, a photocurrent polarity switching photoelectrochemical (PEC)-electrochemical (EC) dual-mode sensing platform was presented for highly selective and sensitive detection of TBE by ingeniously tailor signal probe. The tailored Cu2O@CuO-hemin acting as both photocurrent polarity reversal and electroactivity factor were cross-linked with TBE-BSA to obtain competitive conjugates for TBE. When the competitive response was initiated, numerous of Cu2O@CuO-hemin nanocomposites are introduced on the CdS-modified indium tin oxide electrode, serving as the reporting agent of EC/PEC dual-mode assay. The photocurrent polarity of the CdS-modified ITO can be effectively switched, enabling PEC analysis of TBE with distinguishing photocurrent changes. The linear response range is 1 pg/mL to 500 ng/mL, and the detection limit is 15.0 fg/mL. Meanwhile, the Cu2O@CuO could triggered the amplified current variations via effectually catalyzing the H2O2 decomposition compared to the CdS NPs, leading to the sensitive electrochemical detection of TBE with a detection limit 200 fg/mL and a linear response range from1 pg/mL to 500 ng/mL. Additionally, the developed sensing platform enabled mutual authentication of PEC/EC detection results, being conducive to increasing the assay reliability and accuracy. Such the dual-mode sensor has great potential for detecting environmental pollutants due to its improved selectivity and mutual authentication of results.

A simple lable-free aptasensor based on liquid exfoliated graphene modified electrode for chloramphenicol detection in milk

Antibiotic residues in animal derived foods considered as one of the most serious food contamination poses significant risks to human health. Conventional methods for antibiotic residue detection rely on expensive and bulky instruments, complicated sample pretreatment and time-consuming, thus limiting their applications. Consequently, developing miniaturized and low-cost analytical technology for ultrasensitive monitoring and accurate evaluation of antibiotic residues in foods is of great significance. Herein, a simple and label-free electrochemical sensing platform for the highly sensitive detection of chloramphenicol (CAP) in milk was demonstrated by employing aptamer specific for CAP as a biological recognition element and liquid exfoliated graphene (LEG) modified indium tin oxide electrode (LEG/ITO) as substrate. LEG is believed to be the most economic few-layer graphene with remarkable electrical properties and larger specific surface area not only promotes electron transfer but also provides a large number of binding sites for aptamers to be assembly immobilized via the π–π stacking of DNA bases. Under optimal experimental factors, the aptasensor displayed a wider linear range for detecting CAP (1 fM ∼ 100 nM), accompanied by a limit of detection (LOD) (1 fM), as well as satisfactory performance with specificity, reproducibility, and stability. In addition, the designed strategy allowed the direct analysis of actual milk samples and the recovery rates were from 97.92 % to 103.34 %, rendering a ideal sensing strategy for quantitative determination of various analytes in food by adapting the specific aptamer.

Electrochemical Sensing of Paracetamol Using Functionalized MWCNTs: Integrating Computational and Experimental Methods

An electrochemical sensing platform for the detection of paracetamol is proposed in this work. The sensor (Asp‐MWCNTs/IL/ITO) is based on Indium Tin Oxide (ITO) electrode loaded with asparagine functionalised Multi Walled Carbon Nanotubes (MWCNTs) and Ionic Liquid (IL). Initially, in‐silico studies were performed to check the favourable interaction of the drug with the nanocomposite. The potential energy surface of Asp‐MWCNTs and paracetamol complexes were explored using density functional theory and single‐point energy coupled cluster calculations. The analysis of non‐covalent interactions showed hydrogen bonding interactions predominantly stabilising the complex. The interaction process between Asp‐MWCNTs and paracetamol is spontaneous due to negative value of binding energy (‐0.75 eV). The functionalised MWCNTs were characterised through different techniques. Asp‐MWCNTs/IL/ITO electrode showed good sensitivity with a linear range from 20 – 300 μgL−1 and limit of detection of 0.0194 μM for paracetamol in phosphate buffer as supporting electrolyte. The sensor showed excellent repeatability and reproducibility with a relative standard deviation of 1.45% at 60 μgL−1 concentration. The chemical functionalization resulted in providing extra stability as it retained 95% of its signal response even after 45 days. The sensor’s applicability was tested in real water samples with the help of spiking study which showed good recovery >95%.”

Ultra-sensitive immobilization-free homogeneous electrochemiluminescence biosensor for thrombin detection via electrostatic interaction and Exo I-powered signal amplification

Herein, we present the development of an ultra-sensitive immobilization-free homogeneous electrochemiluminescence (ECL) biosensor, leveraging the electrostatic repulsion between a negatively charged indium tin oxide (ITO) electrode and DNA and exonuclease I (Exo I)-powered signal amplification, to achieve highly efficient detection of thrombin. Specifically, the aptamer and the complementary DNA engage in the formation of a double-stranded DNA (dsDNA) complex. This negatively charged dsDNA structure subsequently associates with a positively charged ECL indicator, namely ruthenium phenanthroline (Ru(phen)32+), resulting in the generation of the dsDNA-Ru(phen)32+ ECL probe. The negatively charged dsDNA-Ru(phen)32+ experiences electrostatic repulsion from the negatively charged ITO electrode, resulting in a low ECL signal. Nonetheless, upon the addition of thrombin, the aptamer preferentially binds to thrombin, triggering the releases of the embedded Ru(phen)32+ facilitated by Exo I and hence resulting in a robust and enhanced ECL signal. The amplified ECL signal is linearly correlated with the logarithm of thrombin concentration within a detection range spanning from 10 fmol/mL to 50 pmol/mL, with a remarkable detection limit of 3.21 fmol/mL. This strategy eliminates the need for cumbersome labeling steps, avoids the electrode modification process, overcoming the low immobilization efficiency of aptamers and poor signal transduction of indicators labeled at the end of DNA.

The Swiss Army Knife of Electrodes: Pillar[6]arene-Modified Electrodes for Molecular Electrocatalysis Over a Wide pH Range.

Molecularly-modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4-10.8 and can be equipped with electrochemically active ruthenium complexes through host-guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]-modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions.

The Swiss Army Knife of Electrodes: Pillar[6]arene‐Modified Electrodes for Molecular Electrocatalysis Over a Wide pH Range

AbstractMolecularly‐modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4–10.8 and can be equipped with electrochemically active ruthenium complexes through host–guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]‐modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions.

Solid-phase electrochemiluminescence immunosensing platform based on bipolar nanochannel array film for sensitive detection of carbohydrate antigen 125.

Development of simple solid-phase electrochemiluminescence (ECL) immunosensor with convenient fabrication for high-performance detection of tumor biomarkers is crucial. Herein, a solid-phase ECL immunoassay was constructed based on a bipolar silica nanochannel film (bp-SNA) modified electrode for highly sensitive detection of carbohydrate antigen 125 (CA 125). Inexpensive and readily available indium tin oxide (ITO) electrode was used as the supporting electrode for the growth of bp-SNA. bp-SNA consists of a bilayer SNA film with different functional groups and charge properties, including negatively charged inner layer SNA (n-SNA) and positively charged outer layer SNA (p-SNA). The nanochannels of bp-SNA were used for the immobilization of ECL emitter tris(bipyridine)ruthenium(II), while the outer surface was utilized for constructing the immunorecognition interface. Due to the dual electrostatic interaction composed of electrostatic attraction from n-SNA and electrostatic repulsion from p-SNA, ECL emitter could be stably confined within bp-SNA, providing stable and high ECL signals to the modified electrode. After amino groups on the outer surface of bp-SNA were derivatized with aldehyde groups, recognition antibodies could be covalently immobilized, and an immunosensor was obtained after blocking nonspecific sites. When CA 125 binds to the antibodies on the recognition interface, the formed complex reduces the diffusion of the co-reactant tripropylamine (TPrA) to the supporting electrode, decreasing the ECL signal. Based on this mechanism, the constructed immunosensor can achieve sensitive ECL detection of CA 125. The linear detection range is from 0.01 to 100U/mL, with a detection limit of 4.7mU/mL. CA 125 detection in serum is also achieved. The construction immunosensor has advantages including simple and convenient fabrication, high stability of the immobilized emitter, and high selectivity, making it suitable for CA 125 detection.

Overcoming the Tradeoff of Visible Transparency and Electrical Conductance via Dual Smoothing of Dielectric/Metal Interfaces in Cu-Thin-Layer-Based Transparent Electrodes.

The rapid advancement of flexible optoelectronic devices, such as light-emitting diodes, solar cells, and electrochromic devices, necessitates the development of high-performance flexible transparent electrodes (TEs). Dielectric/metal/dielectric (DMD)-type TEs are promising alternatives to conventional indium tin oxide (ITO) due to the high electrical conductance, excellent visible transparency, and sufficient mechanical flexibility. However, the tradeoff between electrical conductance and visible transparency poses a challenge to performance enhancement. This study introduces an Ar-ion-mediated interface modification method to address this tradeoff by dual smoothing of dielectric/metal interfaces in TiOx/Cu/ZnO TEs. Implementing this dual smoothing methodology significantly enhances both electrical conductance and visible light transmittance, achieving a Haacke figure of merit 200% higher than that of an unmodified otherwise identical structure. The highest figure of merit is 0.113 Ω-1, a record high for Cu-thin-layer-based DMD TEs, far surpassing ITO electrode values. Further, the enhanced optoelectronic performance remains highly durable under severe and simultaneous electrical, thermal, and mechanical stresses, showcasing the potential for significant advances in flexible optoelectronics.

Stable Halide Perovskite CsPbBr3 Nanocrystals Assisted by Covalent-Organic Frameworks for Electrochemiluminescence Analysis in an Aqueous Medium.

Lead halide perovskites have garnered attention as promising electrochemiluminescence (ECL) emitters owing to their superior photophysical characteristics. However, their poor water stability severely restricts their application in aqueous media for ECL. In this study, inorganic perovskite CsPbBr3 was assembled in situ in the imine-linked covalent-organic framework (COF-LZU1) as a novel ECL emitter. The expansive surface area and robust hydrophobic architecture of COF-LZU1 not only improved the water stability of CsPbBr3 but also guaranteed its exceptional ECL performance. The novel composite nanoluminescent material was coated onto an indium tin oxide (ITO) electrode via spin-coating and calcination processes to serve as an electrochemiluminescence (ECL) platform. A sensor was developed by combining a DNA hydrogel target-induced release system with a platform using ascorbic acid (AA) as a coreactant and T-2 toxin as the target analyte model. This method achieved a detection limit as low as 3.56 fg·mL-1 and was successfully applied to the analysis of the T-2 toxin content in corn samples. This study offers a novel path for the advancement of perovskite-based ECL emitters and their utilization in aqueous environments within the ECL field.

Enhanced Electrochemiluminescence of Luminol and-Dissolved Oxygen by Nanochannel-Confined Au Nanomaterials for Sensitive Immunoassay of Carcinoembryonic Antigen.

Simple development of an electrochemiluminescence (ECL) immunosensor for convenient detection of tumor biomarker is of great significance for early cancer diagnosis, treatment evaluation, and improving patient survival rates and quality of life. In this work, an immunosensor is demonstrated based on an enhanced ECL signal boosted by nanochannel-confined Au nanomaterial, which enables sensitive detection of the tumor biomarker-carcinoembryonic antigen (CEA). Vertically-ordered mesoporous silica film (VMSF) with a nanochannel array and amine groups was rapidly grown on a simple and low-cost indium tin oxide (ITO) electrode using the electrochemically assisted self-assembly (EASA) method. Au nanomaterials were confined in situ on the VMSF through electrodeposition, which catalyzed both the conversion of dissolved oxygen (O2) to reactive oxygen species (ROS) and the oxidation of a luminol emitter and improved the electrode active surface. The ECL signal was enhanced fivefold after Au nanomaterial deposition. The recognitive interface was fabricated by covalent immobilization of the CEA antibody on the outer surface of the VMSF, followed with the blocking of non-specific binding sites. In the presence of CEA, the formed immunocomplex reduced the diffusion of the luminol emitter, resulting in the reduction of the ECL signal. Based on this mechanism, the constructed immunosensor was able to provide sensitive detection of CEA ranging from 1 pg·mL-1 to 100 ng·mL-1 with a low limit of detection (LOD, 0.37 pg·mL-1, S/N = 3). The developed immunosensor exhibited high selectivity and good stability. ECL determination of CEA in fetal bovine serum was achieved.

In-Situ Fabricated Transparent Flexible Nanowire Device with Wavelength-Regulated Dual-Function of Photodetector and Photonic Synapse.

Integrating the dual functionalities of a photodetector and photonic synapse into a single device is challenging due to their conflicting requirements for photocurrent decay rates. This study addresses this issue by seamlessly depositing transparent indium tin oxide (ITO) electrodes onto self-oriented copper hexadecafluoro-phthalocyanine (F16CuPc) nanowires growing horizontally along hot-stamped periodic nanogrooves on a transparent flexible polyimide plastic film. This in-situ-fabricated device achieves bending-stable dual functionalities through wavelength regulation while maintaining high transparency and flexibility. Upon exposure to 450-850 nm light, the device exhibits a rapid and sensitive photoresponse with excellent bending stability, making it ideal for optical sensing in both visible and near-infrared spectra. More importantly, the device exhibits a bending-stable excitation postsynaptic current when exposed to light spikes below 405 nm. This enables the successful emulation of various biological synaptic functionalities, including paired-pulse facilitation, spike-number-dependent plasticity, spike-duration-dependent plasticity, spike-rating-dependent plasticity, configurable plasticity between short-term plasticity and long-term plasticity, and memory learning capabilities. Utilizing this device in an artificial neural network achieves a recognition rate of 95% after 57 training epochs. Its ability to switch between photodetection and synaptic modes by adjusting the light wavelength marks a significant advancement in the field of multifunctional flexible electronics based on nanowire arrays.

A unique and convenient electrochemical biosensor for sodium based on a Na+-pumping rhodopsin

Sodium ion (Na+) detection plays a crucial role in various fields, including clinical diagnostics, environmental monitoring, and food quality control. However, existing techniques often lack sensitivity, selectivity, or practicality. This study presents a novel protein-based electrochemical biosensor for selective and quantitative Na+ detection, utilizing the microbial rhodopsin Nonlabens dokdonensis rhodopsin 2 (NdR2) reconstituted into liposome nanoparticles and immobilized on indium tin oxide (ITO) electrodes. Upon light illumination, the biosensor generates photocurrents proportional to the Na+ concentration in the sample. Extensive characterization unveiled the biosensor’s remarkable selectivity towards Na+ over other cationic species, including K+, Ca2+, Mg2+, and Cs+. Quantitative analysis revealed two linear response ranges: 2–50 mM and 50–200 mM, with a detection limit of 75 μM. The biosensor demonstrated exceptional thermal stability, withstanding 50 °C for 90 min with minimal signal deterioration. Long-term storage stability tests further highlighted its robustness, with consistent Na+ response for up to 17 days. Furthermore, the biosensor successfully detected Na+ in fetal bovine serum, although with a distinct photocurrent profile potentially influenced by interfering components. This pioneering work introduces a highly selective, sensitive, and stable protein-based biosensor for Na+ detection, offering promising implications for diverse applications in clinical diagnostics, environmental monitoring, and quality control, while paving the way for further advancements in biosensing technologies.

Enhanced analog switching and neuromorphic performance of ZnO-based memristors with indium tin oxide electrodes for high-accuracy pattern recognition.

This study systematically investigates analog switching and neuromorphic characteristics in a ZnO-based memristor by varying the anodic top electrode (TE) materials [indium tin oxide (ITO), Ti, and Ta]. Compared with the TE materials (Ti and Ta), memristive devices with TEs made of ITO exhibit dual volatile and nonvolatile switching behavior and multistate switching characteristics assessed based on reset-stop voltage and current compliance (ICC) responses. The polycrystalline structure of the ZnO functional layer sandwiched between ITO electrodes was confirmed by high-resolution transmission electron microscopy analysis. The current transport mechanism in the ZnO-based memristor was dominated by Schottky emission, with the Schottky barrier height modulated from 0.26 to 0.4V by varying the reset-stop voltage under different ICC conditions. The long-term potentiation and long-term depression synaptic characteristics were successfully mimicked by modulating the pulse amplitudes. Furthermore, a 90.84% accuracy was achieved using a convolutional neural network architecture for Modified National Institute of Standards and Technology pattern categorization, as demonstrated by the confusion matrix. The results demonstrated that the ITO/ZnO/ITO/Si memristor device holds promise for high-performance electronic applications and effective ITO electrode modeling.

Microfluidic device with three-dimensional microtip electrodes for efficient capture and concentration of bacteria-sized microparticles using dielectrophoresis

Microfluidics-based systems have gained considerable attention in the lab-on-chip field owing to their ability to separate, concentrate, and analyze microparticles. Concentrating microparticles is crucial for the high-sensitivity measurement of biomarkers in the analysis of cells or bacteria. This study presents a microfluidic chip using dielectrophoresis (DEP) to capture bacterial microparticles. The chip features a vertically arranged microtip electrode and an indium tin oxide (ITO) electrode, enhancing the electric field concentration effect and enabling optical analysis of the collected particles. The device was designed and fabricated using microfabrication techniques that incorporate a patterned array of microtip electrodes on a polydimethylsiloxane (PDMS) substrate. Experimental studies and numerical simulations were conducted to evaluate the device performance. The fabricated device was applied to the concentration of fluorescent beads with various variables such as particle size, frequency, voltage, and flow rate. The experimental results demonstrated the successful trapping and concentration of microparticles using DEP forces. The recovery rates of the 2.29 µm and 4.42 µm PS beads, when introduced at a flow rate of 1 μL/min and subjected to an applied alternating current (AC) voltage of 200 kHz and 10 Vpp at the microtip electrode, were measured to be 85.50±2.69 % and 91.83±0.63 %, respectively. Additionally, to assess the applicability of the microtip electrode-based DEP device proposed here for bacteria concentration, capture experiments were conducted using Escherichia coli, demonstrating a recovery rate performance of 77.93±7.31 %. These findings highlight the potential of the proposed microfluidic chip for the concentration and measurement of bacteria, such as E. coli.