Charge Modulation Research Articles

A modified gate oxide tunnel Field-Effect transistor (TFET) biosensor to identify receptor Tyrosine-Protein kinase 2 (C-erbB-2) in Serum/Saliva

This research demonstrates an analysis of a modified gate oxide tunnel field-effect transistor (TFET) with pocket (Poc-MGOTFET) biosensor for the incredibly sensitive and real-time identification of the breast cancer (BC) biomarker receptor tyrosine-protein kinase (C-erbB-2) in serum and saliva. This research investigates the impact of interface charge modulation in Poc-MGOTFET biosensor with embedded cavities for rapid, accurate, and reliable identification of antigens in bodily fluids, like serum and saliva. The TCAD Sentaurus is used to numerically simulate the proposed biosensor in 2D. The dual cavity etched underneath the dual gate electrode of the proposed biosensor facilitates biomolecule immobilization. This enhances the ability of biomolecules to regulate the source/channel tunneling rate and the proposed biosensor’s electrical performance metrics. A numerical model is developed for the interface charge equivalent of the C-erbB-2. The sensitivity of the device to different C-erbB-2 concentrations in serum/saliva has been studied. The results of our research demonstrate that Poc-MGOTFET, featuring an extended gate structure, modified gate oxide, and pocket along the source side, reduces the leakage current (ILeakage) and OFF current (IOFF), enhances the probability of tunneling, boosts gate control for a greater ON current (ION) and ION/IOFF ratio, and increases sensitivity. Moreover, increased sensitivity by an order of magnitude 106 results from the effect of interface charges corresponding to varying concentrations of C-erbB-2 biomarkers on the sensitivity of the biosensor (as measured by the ION/IOFF ratio).

Using Molecular Structure to Tune Intrachain and Interchain Charge Transport in Indacenodithiophene-Based Copolymers.

In this work, we compare two structurally near-amorphous rigid-rod polymers─poly(indacenodithiophene-co-benzothiadiazole), p(IDT-BT), and poly(indacenodithiophene-co-benzopyrollodione), p(IDT-BPD)─with orders of magnitude different mobilities to understand the effect charge carrier intrachain delocalization has on electronic transport. Quantum chemical calculations show that p(IDT-BPD) has a barrier to torsion that is significantly lower than that of p(IDT-BT) and is thus more likely to have reduced conjugation lengths. We utilize absorption and photoluminescence spectroscopy to characterize energetic disorder and show that p(IDT-BPD) has higher energetic disorder. Charge modulation spectroscopy (CMS) and model calculations are used to show that charge carriers are substantially delocalized in p(IDT-BT) and occupy near-uniform energetic environments. We find that mobility activated hopping barriers are similar in these two materials. Electronic structure calculations show that both intrachain and interchain couplings of monomer units are poor enough in p(IDT-BPD) that charge carriers collapse to single IDT units and transport via a through-space tunneling mechanism. This work highlights the remarkable charge transport properties of p(IDT-BT) by showing that high mobilities are achievable on device-relevant length scales with only 1D carrier delocalization.

Discovery of a long-ranged charge order with 1/4 Ge1-dimerization in an antiferromagnetic Kagome metal

Exotic quantum states arise from the interplay of various degrees of freedom such as charge, spin, orbital, and lattice. Recently, a short-ranged charge order (CO) was discovered deep inside the antiferromagnetic phase of Kagome magnet FeGe, exhibiting close relationships with magnetism. Despite extensive investigations, the CO mechanism remains controversial, mainly because the short-ranged behavior hinders precise identification of CO superstructure. Here, combining multiple experimental techniques, we report the observation of a long-ranged CO in high-quality FeGe samples, which is accompanied with a first-order structural transition. With these high-quality samples, the distorted 2 × 2 × 2 CO superstructure is characterized by a strong dimerization along the c-axis of 1/4 of Ge1-sites in Fe3Ge layers, and in response to that, the 2 × 2 in-plane charge modulations are induced. Moreover, we show that the previously reported short-ranged CO might be related to large occupational disorders at Ge1-site, which upsets the equilibrium of the CO state and the ideal 1 × 1 × 1 structure with very close energies, inducing nanoscale coexistence of these two phases. Our study provides important clues for further understanding the CO properties in FeGe and helps to identify the CO mechanism.

Enzyme-Triggered Degradation of Supramolecularly Cross-Linked Polymersomes of Azobenzene-Based Polyurethane: Cell-Selective Anticancer Drug Release.

Enzyme-responsive self-assembled nanostructures for drug delivery applications have gained a lot of attention, as enzymes exhibit dysregulation in many disease-associated microenvironments. Azoreductase enzyme levels are strongly elevated in many tumor tissues; hence, here, we exploited the altered enzyme activity of the azoreductase enzyme and designed a main-chain azobenzene-based amphiphilic polyurethane, which self-assembles into a vesicular nanostructure and is programmed to disassemble in response to a specific enzyme, azoreductase, with the help of the nicotinamide adenine dinucleotide phosphate (NADPH) coenzyme in the hypoxic environment of solid tumors. The vesicular nanostructure sequesters, stabilizes the hydrophobic anticancer drug, and releases the drug in a controlled fashion in response to enzyme-triggered degradation of azo-bonds and disruption of vesicular assembly. The biological evaluation revealed tumor extracellular matrix pH-induced surface charge modulation, selective activated cellular uptake to azoreductase overexpressed lung cancer cells (A549), and the release of the anticancer drug followed by cell death. In contrast, the benign nature of the drug-loaded vesicular nanostructure toward normal cells (H9c2) suggested excellent cell specificity. We envision that the main-chain azobenzene-based polyurethane discussed in this manuscript could be considered as a possible selective chemotherapeutic cargo against the azoreductase overexpressed cancer cells while shielding the normal cells from off-target toxicity.

Atomic-level tailoring of single-atom tungsten catalysts for optimized electrochemical nitrate-to-ammonia conversion

Nitrate contamination of water resources poses significant health and environmental risks, necessitating efficient denitrification methods that produce ammonia as a desirable product. The electrocatalytic nitrate reduction reaction (NO3RR) powered by renewable energy offers a promising solution, however, developing highly active and selective catalysts remains challenging. Single-atom catalysts (SACs) have shown impressive performance, but the crucial role of their coordination environment, especially the next-nearest neighbor dopant atoms, in modulating catalytic activity for NO3RR is underexplored. This study aims to optimize the NO3RR performance of tungsten (W) single atoms anchored on graphene by precisely engineering their coordination environment through first and next-nearest neighbor dopants. The stability, reaction paths, activity, and selectivity of 43 different nitrogen and boron doping configurations were systematically studied using density functional theory. The results reveal W@C3, with W coordinated to three carbon atoms, exhibits outstanding NO3RR activity with a low limiting potential of −0.36 V. Intriguingly, introducing next-nearest neighbor B and N dopants further enhances the performance, with W@C3-BN achieving a lower limiting potential of −0.26 V. This exceptional activity originates from optimal nitrate adsorption strengths facilitated by orbital hybridization and charge modulation effects induced by the dopants. Furthermore, high energy barriers for NO2 and NO formation on W@C3 and W@C3-BN ensure their selectivity towards NO3RR products. These findings provide crucial atomic-level insights into rational design strategies for high-performance single-atom NO3RR catalysts via coordination environment engineering.

Terahertz spectroscopy of collective charge density wave dynamics at the atomic scale.

Charge density waves are wave-like modulations of a material's electron density that display collective amplitude and phase dynamics. The interaction with atomic impurities induces strong spatial heterogeneity of the charge-ordered phase. Direct real-space observation of phase excitation dynamics of such defect-induced charge modulation is absent. Here, by utilizing terahertz pump-probe spectroscopy in a scanning tunnelling microscope, we measure the ultrafast collective dynamics of the charge density wave in the transition metal dichalcogenide 2H-NbSe2 with atomic spatial resolution. The tip-enhanced electric field of the terahertz pulses excites oscillations of the charge density wave that vary in magnitude and frequency on the scale of individual atomic impurities. Overlapping phase excitations originating from the randomly distributed atomic defects in the surface create this spatially structured response of the charge density wave. This ability to observe collective charge order dynamics with local probes makes it possible to study the dynamics of correlated materials at the intrinsic length scale of their underlying interactions.

Prototype Design Remote Smart Car 4WD Robot Car with Additional Power Photovoltaic Source Integrated Arduino

The problem addressed in this research is designing an Electric Car Prototype, a technology design using Arduino Uno, L298N Driver Module, and HC-06 Bluetooth sensor which is controlled automatically using an application. The method used is a hybrid PLTS (Solar Power Plant) system based on Arduino Uno. This prototype combines electrical energy from batteries with solar energy produced by solar panels, and the main controller is Arduino Uno. Tests were carried out to evaluate the performance and efficiency of this electric car. The results of solar panel experiments in designing electric car prototypes, testing will be carried out on the efficiency of solar panels on the power produced. The following is the data from the experimental results measured through the following table 2 experiments. solar panels were installed on the roof or other parts exposed to sunlight on a prototype electric car. Solar panels consist of photovoltaic solar cells which are capable of converting solar energy into electrical energy. When sunlight falls on a solar panel, the solar cell produces an electric current. The electric current generated from the solar cell is then channeled to the charging module to charge the battery. The battery charging module regulates the voltage and electric current according to battery charging needs. This is important so that the battery does not receive too much or too little power during the charging process. After passing through the battery charging module, the electrical energy from the solar panels is used to charge the electric car battery. Electric car batteries function as energy storage which is used to control the engine and other electronic systems in the car. Obtained were the development of an environmentally friendly and sustainable electric vehicle.

Charge modulation of selenospinel by Mn modification to generate unsaturated Se sites for highly efficient mercury capture

Selenospinel has been regarded as a promising adsorbent for Hg0 capture from the flue gas, and the unsaturated Se1− site is one of the critical factors affecting the Hg0 capture performance. The regulation of selenospinel to generate more unsaturated Se1− sites is a great challenge for the enhanced Hg0 capture performance. Herein, a charge modulation strategy of selenospinel via high-valance Mn modification was proposed to generate the unsaturated Se1− sites for efficient and fast Hg0 capture. The unsaturated Se1− sites showed the high affinity towards Hg0 and decreased the energy barrier of HgSe formation. As a result, Mn modified CuCo2Se4 spinel showed the ultra-high Hg0 adsorption capacity (125.86 mg·g−1) and rate (10.24 mg·g−1∙h−1), which were greatly higher than the previously reported adsorbents. Additionally, Mn modified CuCo2Se4 exhibited the excellent resistance towards SO2 and H2O, making it highly suitable for the practical application. DFT calculation verified the important role of unsaturated Se1− sites derived from Mn modification in the Hg0 removal process. This study developed a metal modification strategy to modulate the charge distribution of selenospinel for Hg0 capture, offering a guidance for adsorbent design in the environmental protection.

Modulating zero charge potential of Zn-doped N, P-containing carbon electrodes for efficient copper ion electrosorption

Nitrogen/phosphorus (N/P) doped carbon materials exhibit enhanced electro adsorption capability in capacitive deionization (CDI) applications. However, the incorporation of N/P atoms may introduce electron-withdrawing groups to the electrode surface, impacting the potential of zero charge (EPZC) and thereby influencing its electro adsorption efficiency. This research explores the modulation of electrode surface charge by varying the N/P doping composition. Specifically, it presents a Zn and N/P co-doped carbon material employed as the CDI cathode, showcasing selective adsorption of Cu2+ ions. Under a voltage of 1.2 V, the adsorption capacity achieves 250 mg/g in a 500 mg/L Cu2+ ion solution. Furthermore, it demonstrates outstanding cycling stability, maintaining an adsorption capacity of 233 mg/g even after 21 cycles. This investigation introduces an innovative approach for EPZC adjustment and offers a fresh theoretical framework for fabricating high-performance CDI electrodes.

Remotely Controlled Surface Charge Modulation of Magnetoelectric Nanogenerators for Swift and Efficient Drug Delivery.

We have developed a highly efficient technique of magnetically controlled swift loading and release of doxorubicin (DOX) drug using a magnetoelectric nanogenerator (MENG). Core-shell nanostructured MENG with a magnetostrictive core and piezoelectric shell act as field-responsive nanocarriers and possess the capability of field-triggered drug release in a cancerous environment. MENGs generate a surface electric dipole when subjected to a magnetic field due to the strain-mediated magnetoelectric effect. The capability of directional magnetic field-assisted modulation of the surface electrical dipole of MENG provides a mechanism to create/break ionic bonds with DOX molecules, which facilitates efficient drug attachment and on-demand swift detachment of the drug at a targeted site. The magnetic field-assisted drug-loading mechanism was minutely analyzed using spectrophotometry and Raman spectroscopy. The detailed time-dependent analysis of controlled drug release by the MENG under unidirectional and rotating magnetic field excitation was conducted using field-emission scanning electron microscopy, energy-dispersive X-ray, and atomic force microscopic measurements. In vitro, experiments validate the cytocompatibility and magnetically assisted on-demand and swift DOX drug delivery by the MENG near MCF-7 breast cancer cells, which results in a significant enhancement of cancer cell killing efficiency. A state-of-the-art experiment was performed to visualize the nanoscale magnetoelectric effect of MENG using off-axis electron holography under Lorentz conditions.

Combined antibacterial and antifouling properties of polyethersulfone mixed matrix membranes with zwitterionic graphene oxide nanostructures

AbstractThe impact of zwitterionic graphene oxide (GO‐Arg) nanostructures into polyethersulfone (PES) membranes was studied, aiming to perform mixed matrix membranes (MMMs) with combined antibacterial and antifouling properties. For this purpose, 0.25, 0.50, and 1.0 wt% of GO‐Arg were incorporated through the phase inversion method. The chemical composition reveals that the electrostatic interactions of PES, polyvinylpyrrolidone, and GO‐Arg occur by enhancing the CH/NH vibrations associated with the intrinsic MMMs and their combined antibacterial and antifouling performance. Well‐defined finger‐like morphology was observed, performing the pore distribution and the finger‐cavity inclination induced by the electrostatic charge of GO‐Arg. As a result, GO‐Arg MMM's hydrophobic properties decreased from 77.8° to 52.3°, inducing a partially hydrophilic surface and improved water flux. The isoelectric point of nanostructured membranes slightly changes by the charge modulation produced by zwitterionic GO‐Arg. The antibacterial activity against Gram (−) Escherichia coli was improved, closing the complete bacterial inhibition after 24 h. As a result, antifouling performance was improved, avoiding bacterial adhesion into the membrane surface and the possibility of promoting biofilm formation. Our results demonstrate that zwitterionic nanomaterials in MMMs perform the multifunctional capacity of materials, emerging as an effective alternative with potential application in wastewater treatment.Highlights The incorporation of zwitterionic GO‐Arg improves the mechanical properties of MMMs. GO‐Arg‐enhanced well‐defined porous finger‐like morphology in MMMs. GO‐Arg improves the antibacterial/antifouling performance of PES‐based MMMs.

Interplay of space charge, intrabeam scattering, and synchrotron radiation in the Compact Linear Collider damping rings

Future ultralow emittance rings for e−/e+ colliders require extremely high beam brightness and can thus be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intrabeam scattering (IBS), and space charge in the vicinity of excited betatron resonances is assessed. In this respect, two algorithms were developed to simulate IBS and synchrotron radiation effects and integrated in the y tracking code, to be combined with its widely used space charge module. The impact of these effects on the achievable beam parameters of the Compact Linear Collider (CLIC) damping rings was studied, showing that synchrotron radiation damping mitigates the adverse effects of IBS and space charge induced resonance crossing. The studies include also a full dynamic simulation of the CLIC damping ring cycle starting from the injection beam parameters. It is demonstrated that a careful working point choice is necessary, in order to accommodate the transition from detuning induced by lattice nonlinearities to space-charge dominated detuning and thereby avoid excessive losses and emittance growth generated in the vicinity of strong resonances. Published by the American Physical Society 2024

Light‐Induced Ferroelectric Modulation of p‐n Homojunctions in Monolayer MoS2

AbstractThe association of 2D materials and ferroelectrics offers a promising approach to tune the optoelectronic properties of atomically thin Transition Metal Dichalcogenides (TMDs). In this work, the combined effect of ferroelectricity and light on the optoelectronic properties of monolayer (1L)‐MoS2 deposited on periodically poled lithium niobate crystals is explored. Using scanning micro‐photoluminescence, the effect of excitation intensity, scanning direction, and domain walls on the 1L‐MoS2 photoluminescence properties is analyzed, offering insights into charge modulation of MoS2. The findings unveil a photoinduced charging process dependent on the ferroelectric domain orientation, in which light induces charge generation and transfer at the monolayer‐substrate interface. This highlights the substantial role of light excitation in ferroelectrically‐driven electrostatic doping in MoS2. Additionally, the work provides insights into the effect of the strong, nanometrically confined electric fields on LiNbO3 domain wall surfaces, demonstrating precise control over charge carriers in MoS2, and enabling the creation of deterministic p‐n homojunctions with exceptional precision. The results suggest prospects for novel optoelectronic and photonic application involving monolayer TMDs by combining light‐matter interaction processes and the surface selectivity provided by ferroelectric domain structures.

Dual-drive strategy-based modulation of the interfacial charge of S-scheme heterojunction and photoelectrochemical ultrasensitive detection of CD44

The efficacy of charge carrier separation plays a crucial role in influencing the practical application of photoelectrochemical (PEC) detection platforms, which can be meticulously engineered to realize highly sensitive detection at the sensing interface. Hence, a novel dual-drive strategy was proposed to integrate thermally-assisted external drive behavior with the internal drive behavior of sulfur vacancies (SVs), realizing the rapid separation of charge at the S-scheme heterojunction sensing interface. On the one hand, unabsorbed solar energy was utilized an external driving force to facilitate efficient photothermoelectric conversion within the In2S3/CdS heterojunction, achieving the photocurrent response intensity 1.5 times higher than conventional PEC detection methods. On the other hand, introducing sulfur vacancies (SVs) as internal driving forces induced ordered migration and directional flow of charge carriers. Moreover, density functional theory (DFT) calculations and experimental results demonstrated that photo-generated carriers achieved rapid separation along the S-scheme heterojunction. Under the optimal conditions, a biosensor constructed based on the dual-drive strategy exhibited high sensitivity for the CD44 (cluster of differentiation-44) cluster, with a low detection limit of 0.132 pg mL−1and a wide linear range of 0.001 ∼ 1000 ng mL−1. The proposed strategy offers new insights into how to effectively harness excess energy in the traditional ultraviolet spectral range for ultrasensitive biosensors.

Inhomogeneous high temperature melting and decoupling of charge density waves in spin-triplet superconductor UTe2

Charge, spin and Cooper-pair density waves have now been widely detected in exotic superconductors. Understanding how these density waves emerge — and become suppressed by external parameters — is a key research direction in condensed matter physics. Here we study the temperature and magnetic-field evolution of charge density waves in the rare spin-triplet superconductor candidate UTe2 using scanning tunneling microscopy/spectroscopy. We reveal that charge modulations composed of three different wave vectors gradually weaken in a spatially inhomogeneous manner, while persisting to surprisingly high temperatures of 10–12 K. We also reveal an unexpected decoupling of the three-component charge density wave state. Our observations match closely to the temperature scale potentially related to short-range magnetic correlations, providing a possible connection between density waves observed by surface probes and intrinsic bulk features. Importantly, charge density wave modulations become suppressed with magnetic field both below and above superconducting Tc in a comparable manner. Our work points towards an intimate connection between hidden magnetic correlations and the origin of the unusual charge density waves in UTe2.

Temperature-Driven Rotation Symmetry-Breaking States in an Atomic Kagome Metal KV3Sb5.

Kagome lattice AV3Sb5 has attracted tremendous interest because it hosts correlated and topological physics. However, an in-depth understanding of the temperature-driven electronic states in AV3Sb5 is elusive. Here we use scanning tunneling microscopy to directly capture the rotational symmetry-breaking effect in KV3Sb5. Through both topography and spectroscopic imaging of defect-free KV3Sb5, we observe a charge density wave (CDW) phase transition from an a0 × a0 atomic lattice to a robust 2a0 × 2a0 superlattice upon cooling the sample to 60 K. An individual Sb-atom vacancy in KV3Sb5 further gives rise to the local Friedel oscillation (FO), visible as periodic charge modulations in spectroscopic maps. The rotational symmetry of the FO tends to break at the temperature lower than 40 K. Moreover, the FO intensity shows an obvious competition against the intensity of the CDW. Our results reveal a tantalizing electronic nematicity in KV3Sb5, highlighting the multiorbital correlation in the kagome lattice framework.

Engineering Charge Density Waves by Stackingtronics in Tantalum Disulfide.

In the realm of condensed matter physics and materials science, charge density waves (CDWs) have emerged as a captivating way to modulate correlated electronic phases and electron oscillations in quantum materials. However, collectively and efficiently tuning CDW order is a formidable challenge. Herein, we introduced a novel way to modulate the CDW order in 1T-TaS2 via stacking engineering. By introducing shear strain during the electrochemical exfoliation, the thermodynamically stable AA-stacked TaS2 consecutively transform into metastable ABC stacking, resulting in unique 3a × 1a CDW order. By decoupling atom coordinates, we atomically deciphered the 3D subtle structural variations in trilayer samples. As suggested by density functional theory (DFT) calculations, the origin of CDWs is presumably due to collective excitations and charge modulation. Therefore, our works shed light on a new avenue to collectively modulate the CDW order via stackingtronics and unveiled novel mechanisms for triggering CDW formation via charge modulation.

Ultrahigh Salt Adsorption Capacity of Carbonaceous Electrode in a Rocking-Chair Capacitive Deionization through Surface Charge Modulation

Ultrahigh Salt Adsorption Capacity of Carbonaceous Electrode in a Rocking-Chair Capacitive Deionization through Surface Charge Modulation

Advancements in bifunctional catalysts for unitized regenerative fuel cells: exploring polaronic conduction and heterostructure designs

This study investigates the development and performance evaluation of a bifunctional catalyst tailored for unitized regenerative fuel cells (URFCs), capable of facilitating both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in fuel cell and electrolyzer modes. The primary challenge addressed is the creation of electrocatalysts exhibiting high activity and corrosion resistance for oxygen reduction and water oxidation at the oxygen electrode. A novel catalyst structure based on La0.5Sr0.5Fe0.5Ti0.5O3(LSFT), i.e. LSFT/ZnO/LSFT with a thickness of ∼2 μ m, is explored within an environmentally friendly medium. This catalyst demonstrates superior performance characteristics, including reduced overpotential in HER and enhanced stability during oxygen/hydrogen evolution processes in neutral medium. This study identifies the formation of interfacial polarons and polaronic charge modulation resulting from the incorporation of ZnO in LSFT, leading to multifunctional OER/HER behavior. Notably, the proposed interfacial small polaron mechanism offers valuable insights into complex interfacial phenomena and holds promise for applications in diverse heterostructures involving layered 2D materials and transition metal oxides. Moreover, the robust LSFT/ZnO/LSFT catalyst exhibits exceptional stability, maintaining for 168 h of oxygen evolution at a constant potential of approximately 1.66 V for a current density of 1 A cm−2 in a neutral medium. These findings mark a significant advancement in URFC technology and present promising avenues for clean energy storage solutions.

Super-Nernstian pH detection using out-of-equilibrium body potential in silicon on insulator ISFET sensors: Proof-of-concept and optimization paths

In this work, we demonstrate pH sensing using the out-of-equilibrium body potential (VB) monitored in silicon-on-insulator (SOI) double-gate “ISFET-like” devices with deposited metal contacts. Similar to the behavior of a dual-gate ISFET, in this study, the conductive channel induced by the back-gate voltage at the silicon/buried oxide (Si/BOX) interface is modulated by the charges to-be-sensed that are intentionally placed on the top silicon oxide layer SiO2 covering the Si film. The detection of the surface charge modulation was evidenced by monitoring in real-time the out-of-equilibrium body potential, while the classic shift in the drain current served as control experiment and for benchmarking. These first experiments demonstrate the successful implementation of this new pH detection paradigm, with super-Nernstian sensitivity. To provide optimization options for the body-potential sensing, TCAD simulations of the pH sensors were performed in a 2D structure and illustrated the possibility to further enhance the device sensitivity with an optimized architecture. Moreover, the pH-induced shift occurs at very high applied gate biases for the drain current, contrary to the body potential, which implies a sensor with lower power consumption when VB is used as reading method. Thus, body potential monitoring provides a promising reading method to reach the required low-power consumption regime of the tomorrow’s sensing devices.