Stable Switching Research Articles

Artificial Tactile Sensing Neuron with Tactile Sensing Ability Based on a Chitosan Memristor.

Owing to the highly parallel network structure of the biological neural network and its triggered processing mode, tactile sensory neurons can realize the perception of external signals and the functions of perception, memory, and data processing by adjusting the synaptic weight. In this paper, a piezoresistive pressure sensor is combined with a memristor to design an artificial tactile sensory neuron. The polyurethane sponge sensor has excellent sensitivity and can convert physical stimuli into electrical signals, and the chitosan-based memristor has stable bipolar resistive switching characteristics, allowing further information to be memorized and processed. The neuron can respond to tactile stimuli of different degrees, durations, and frequencies; realize potentiation/depression modulation, paired-pulse facilitation, and spike-timing-dependent plasticity; exhibit spike-rate-dependent plasticity; and store and erase tactile information through memistor state switching, which has great application potential in biological sensing systems.

Unusual magnetic behavior in Dy-doped LuFe0.5Cr0·5O3 perovskite ceramics

In this paper, polycrystalline Lu1-xDyxFe0.5Cr0·5O3 (0≤x≤0.15) perovskite ceramics were synthesized via a conventional solid-state-reaction technique. Structural and magnetic properties of the samples were experimentally studied. The cell volume of the lattice expands with the rise in Dy3+ amount. The measuring of magnetic properties shows that the undoped sample exhibits a negative magnetization effect with a compensation temperature of 231.1 K, while the Dy-doped samples display negative magnetization effects between two compensation temperatures. The magnetic switch experiment demonstrates the significant potential for practical applications through stable and repeatable switching of magnetization state by adjusting the external magnetic field between 50 Oe and 300 Oe. Besides, the presence of two compensation temperatures which can be regulated by changing the doping content or external magnetic field provides more possibilities for application. Moreover, based on the comprehensive analysis of the experimental results, it is believed that the negative magnetization effect originates from the competition of magnetic moments in different directions. Meanwhile, the second compensation temperature occurs in low temperature region might be attributed to the additional positive magnetic moment contributed by the paramagnetic Dy3+ ions.

Fish survival subject to algal bloom: Resource-based growth models with algal digestion delay and detritus-nutrient recycling delay

In this paper, we propose a class of resource-based growth models with delays in algal digestion and detritus-nutrient recycling, and investigate the model based on two different survival scenarios of algae during nutrient transformation. One scenario considers the survival rates of algae during nutrient uptake, while the other overlooks this factor. We find a significant difference in the estimated time window required for clearing the lake of detritus between the two models, and both are longer compared to the model without algal digestion delay. Moreover, the internal equilibria of both scenarios undergo an infinite number of stability switches, however, the key parameters leading to these stability switches differ. Notably, in the model accounting for algal death during nutrient uptake, there exists a safe zone where the stability of the internal equilibrium remains unaffected by the detritus-nutrient recycling delay, provided that the algal digestion delay falls within a suitable range. The findings derived from this study can provide valuable insights for the development of efficacious approaches in safeguarding the ecological integrity, managing algal blooms, facilitating sustainable fishery practices, and fostering favorable economic outcomes within the realm of water resources advancement.

Double Hopf bifurcation analysis of time delay coupled active control system

In this paper, the stability analysis of double Hopf bifurcation is carried out based on the time delay coupled active control system by using the related theory of bifurcation analysis. We got the stability switching region of the system with respect to time delay. The time delay and coupling strength are selected as the bifurcation parameters, then the normal form of the coupled time delay active control system is obtained by using the multi-scale method, and the dynamic behavior near the bifurcation point is obtained. So the parameter region of the stable periodic solution and the stable quasi-periodic solution are obtained. The analytical solution of the system is then solved by using the multi-frequency homotopy analysis method (MFHAM) to verify the existence of the unstable periodic solution. Finally, numerical simulation is executed to verify the theoretical results.

Stability and Hopf Bifurcation Analysis of A Fractional-Order BAM Neural Network with Two Delays Under Hybrid Control

In this paper, considering that fractional-order calculus can more accurately describe memory and genetic properties, we introduce fractional integral operators into neural networks and discuss the stability and Hopf bifurcation of a fractional-order bidirectional associate memory (BAM) neural network with two delays. In addition, the hybrid controller is proposed to achieve Hopf bifurcation control of the system. By taking two time delays as the bifurcation parameters and analyzing of the corresponding characteristic equation, stability switching curves of the controllable system for two delays are obtained. The direction of the characteristic root crossing the imaginary axis in stability switching curves is determined. Sufficient criteria are sequentially given to judge the local stability and the existence of Hopf bifurcation of a fractional-order BAM neural network system. The numerical simulation results show that the hybrid controller can effectively control Hopf bifurcation of a fractional-order BAM neural network system with two delays.

Effective Descriptor for Screening Single-Molecule Conductance Switches.

The adsorption-type molecular switch exhibits bistable states with an equivalently long lifetime at the organic/inorganic interface, promising reliable switching behavior and superior assembly ability in the electronic circuits at the molecular scale. However, the number of reported adsorption-type molecular switches is currently less than 10, and exploring these molecular switches poses a formidable challenge due to the intricate interplay occurring at the interface. To address this challenge, we have developed a model enabling the identification of diverse molecular switches on metal surfaces based on easily accessible physical characteristics. These characteristics primarily include the metal valency electron concentration, the work function of metal surfaces, and the electronegativity difference of molecules. Using this model, we identified 56 new molecular switches. Employing the gradient descent algorithm and statistical linear discriminant analysis, we constructed an explicit descriptor that establishes a relationship between the interfacial structure and chemical environment and the stability of molecular switches. The model's accuracy was validated through density functional theory calculations, achieving a 90% accuracy for aromatic molecular switches. The conductive switching behaviors were further confirmed by nonequilibrium Green's function transport calculations.

Diarylamines with switchable intramolecular H-bonding: a new approach to molecular logic gates

New ortho-substituted diarylamines prone to different types of the intramolecular H-bonding (IMHB) were obtained. In-depth NMR, IR and voltammetry study allowed selecting the amine that demonstrates stable reversible switching of the IMHB bond under the external stimuli, which can be used for the logic gate construction.

Source-Storage-Load Coordinated Master-Slave Control Strategy for Islanded Microgrid Considering Load Disturbance and Communication Interruption.

When there is a sudden load disturbance in an islanded microgrid, the peer-to-peer control model requires the energy resource to maintain a margin of generation, resulting in a relatively limited regulation range, that is, voltage/frequency sometimes requires additional control to maintain stability. A "source-storage-load" coordinated master-slave control strategy is proposed in this study to address the aforementioned issues. The system voltage and frequency will be stable as long as the output frequency and voltage of the master resource are stable. Furthermore, it can fully utilize the power supply capacity of resources to support the supply-demand balance. The following tasks are included in the proposed strategy: 1) to improve the operational security in the face of load disruption, a source-storage-load coordinated control method based on the "ramping speed" ratio is proposed, which can quickly restore the balance of supply and demand; 2) to improve the communication reliability in the face of interruption, a channel planning method is proposed, which can address the communication interruption problem by constructing an internal network among source-storage-load; and 3) to improve the mode switching stability of resources subjected to external disturbance, the external disturbance suppression and stability analysis involved in the regulation process are completed using sliding-mode control and small signal model methods. Related case studies are carried out to verify the effectiveness of the proposed strategies.

Supramolecular Metal Halide Complexes for High-Temperature Nonlinear Optical Switches.

Nonlinear optical (NLO) switching materials, which exhibit reversible intensity modulation in response to thermal stimuli, have found extensive applications across diverse fields including sensing, photoelectronics, and photonic applications. While significant progress has been made in solid-state NLO switching materials, these materials typically showcase their highest NLO performance near room temperature. However, this performance drastically deteriorates upon heating, primarily due to the phase transition undergone by the materials from noncentrosymmetric to centrosymmetric phase. Here, we introduce a new class of NLO switching materials, solid-state supramolecular compounds 18-Crown-6 ether@Cu2Cl4·4H2O (1·4H2O), exhibiting reversible and stable NLO switching when subjected to near-infrared (NIR) photoexcitation and/or thermal stimuli. The reversible crystal structure in response to external stimuli is attributed to the presence of a weakly coordinated bridging water molecule facilitated by hydrogen bonding/chelation interactions between the metal halide and crown-ether supramolecules. We observed an exceptionally high second-harmonic generation (SHG) signal under continuous photoexcitation, even at temperatures exceeding 110 °C. In addition, the bridging water molecules within the complex can be released and recaptured in a fully reversible manner, all without requiring excessive energy input. This feature allows for precise control of SHG signal activation and deactivation through structural transformations, resulting in a high-contrast off/on ratio, reaching values in the million-fold range.

Modified electronic structure of amorphous Mn‐Si‐Te for OTS application: Improved thermal stability by the formation of Mn‐Te bonding

A critical element within the 3D Xpoint architecture is the Ovonic threshold switch (OTS) material, which serves a crucial role as a selector. The development of novel OTS materials devoid of hazardous elements such as As and Se is imperative for mitigating environmental impact. The Si‐Te binary telluride is a representative As/Se‐free OTS material, demonstrating stable switching. However, its thermal stability is insufficient for enduring annealing processes in semiconductor manufacturing. To address this challenge, this study proposes the incorporation of Mn into the Si‐Te alloy. While the introduction of transition metals into chalcogenide glass typically reduces the electrical resistivity, potentially compromising the ON/OFF ratio, the off current for the device containing 26 at.% Mn is observed to be lower than that for the undoped Si‐Te device. Furthermore, the thermal stability of the Mn‐Si‐Te film surpasses that of its pristine counterpart. X‐ray photoelectron spectroscopy and density functional theory simulations provide evidence of Mn‐Te bonding formation in the Mn‐Si‐Te amorphous alloy, thus suggesting the role of Mn‐Te bonding in enhancing thermal stability. These findings provide a promising avenue for the advancement of novel OTS materials.This article is protected by copyright. All rights reserved.

Monolithically integrated high-density vertical organic electrochemical transistor arrays and complementary circuits.

Organic electrochemical transistors (OECTs) can be used to create biosensors, wearable devices and neuromorphic systems. However, restrictions in the micro- and nanopatterning of organic semiconductors, as well as topological irregularities, often limit their use in monolithically integrated circuits. Here we show that the micropatterning of organic semiconductors by electron-beam exposure can be used to create high-density (up to around 7.2 million OECTs per cm2) and mechanically flexible vertical OECT arrays and circuits. The energetic electrons convert the semiconductor exposed area to an electronic insulator while retaining ionic conductivity and topological continuity with the redox-active unexposed areas essential for monolithic integration. The resulting p- and n-type vertical OECT active-matrix arrays exhibit transconductances of 0.08-1.7 S, transient times of less than 100 μs and stable switching properties of more than 100,000 cycles. We also fabricate vertically stacked complementary logic circuits, including NOT, NAND and NOR gates.

Halogen-Regulated Tc and X-ray Radiation Detection in 2D Hybrid Perovskite Ferroelastic Semiconductor.

Organic-inorganic hybrid perovskites (OIHPs) have received particular attention due to their characteristic structural tunability and flexibility. These features make OIHPs behave with excellent modifications on macroscopic properties, such as ferroicity or semiconductor performances, etc. Herein, we report two 2D hybrid stibium-based halide perovskite (C3H7N)3Sb2X9 (X = Br, 1; Cl, 2) ferroelastic semiconductor possessing dual switching properties of dielectric and second harmonic generation (SHG). Notably, these two hybrids exhibit halogen-regulated ferroelasticity and semiconductor properties. There is a significant difference in Curie temperature (Tc) and X-ray radiation detection sensitivity (S), i.e., the ΔTc and ΔS are 38 K and 87 μC Gyair-1 cm-2, respectively. Meanwhile, crystals 1 and 2 do not show dark current drift in cyclic measurements of different radiation doses with stable switching ratios of 30 and 10, separately. Meanwhile, these results were proven by scientific experimental results and density functional theory (DFT) calculations. Our work presents a facile and practical method to regulate macroproperties on the molecular level, providing a new vision to develop hybrid perovskite ferroic-photoelectric materials.

Delayed nonmonotonic immune response in HIV infection system

In this paper, we study a delayed HIV infection model with nonmonotonic immune response and perform stability and bifurcation analysis. Our results show that the delayed HIV infection system with nonmonotonic immune response has bistability and stable periodic solution appear. We find that both the uninfected and immune‐free equilibria are globally asymptotically stable under certain conditions which are not affected by time delay. However, the time delay makes one immune equilibrium always unstable for and also makes another immune equilibrium appear stability switches; meanwhile, the system will exhibit local Hopf bifurcation, global Hopf bifurcation, and saddle‐node‐Hopf bifurcation. Numerical simulations are carried out to verify our results.

Structural phase transition and resistive switching properties of Cu x O films during post-thermal annealing

We studied the phase change and resistive switching characteristics of copper oxide (Cu x O) films through post-thermal annealing. This investigation aimed to assess the material’s potential for a variety of electrical devices, exploring its versatility in electronic applications. The Cu x O films deposited by RF magnetron sputtering were annealed at 300, 500, and 700 °C in ambient air for 4 min by rapid thermal annealing (RTA) method, and then it was confirmed that the structural phase change from Cu2O to CuO occurred with increasing annealing temperature. Resistive random-access memory (ReRAM) devices with Au/Cu x O/p+-Si structures were fabricated, and the ReRAM properties appeared in CuO-based devices, while Cu2O ReRAM devices did not exhibit resistive switching behavior. The CuO ReRAM device annealed at 500 °C showed the best properties, with a on/off ratio of 8 × 102, good switching endurance of ∼100 cycles, data retention for 104 s, and stable uniformity in the cumulative probability distribution. This characteristic change could be explained by the difference in the grain size and density of defects between the Cu2O and CuO films. These results demonstrate that superior and stable resistive switching properties of RF-sputtered Cu x O films can be obtained by low-temperature RTA.

A Thermoresponsive Lead‐Free Organic‐Inorganic Hybrid Perovskite as a Dielectric Switch

AbstractThermochromic perovskites, renowned for their tunable bandgap, high absorption coefficient, and reversible color changes, emerge as promising candidates for applications in smart windows. These advancements not only have the potential to enhance occupant comfort but also contribute significantly to reducing energy consumption in buildings. Here, we present a two‐dimensional lead‐free organic‐inorganic hybrid perovskite [Cyclobutylammonium]2CuCl4 which shows phase transitions from C2/c to P21/c to P21/c space group at 319.5 K and 348.8 K, respectively. Accompanying these transitions is a fascinating, reversible thermochromic behavior that is dependent on the phase structure. This behavior manifests as a vibrant sequence transitioning from yellow to brown and finally to a slightly dark brown. Most importantly, the demonstrated ability to switch stably between high and low dielectric states indicates the enormous potential of this material as a dielectric switch. This non‐toxic thermoresponsive perovskite, characterized by its appropriate transition temperatures, reversible phase structure‐dependent thermochromism, and stable dielectric switching behavior, is expected to generate significant interest within the fields of thermoresponsive and dielectric switching materials. The integration of these features not only positions this perovskite as a noteworthy subject of scientific inquiry but also opens avenues for practical applications in diverse fields.

The filaments control for tunning digital resistive switching in data storage application and analog behavior as an artificial synapse with CsPbBr3-based memristor

Implementation of tunable digital and analog resistive switching (RS) behaviors for memristors is crucial toward their development in data storage and energy-efficient computations. Herein, the CsPbBr3 film-based RS memristors with different switching film thickness and adaptable electrodes are constructed, which are implemented by the solution processed method. All the constructed memristors demonstrate stable bipolar switching behaviors, and in special, the gradual analog RS behavior with multi-level conductance is observed for the thin memristor, making it as the promising artificial synapse. As a comparison, the thick memristor demonstrates digital abrupt RS behavior, accompanying with a high memory window (>103), which can be applied in data storage field. Furthermore, the evolution of conductive filaments, stemming from synergetic bromine vacancies and aluminum atoms, is proposed to clarify the distinguished dynamic changes in the RS process. This work provides an optimization strategy to tune RS behavior for CsPbBr3-based RS memristors and paves the way for both data storage and artificial synapse applications.

Engineering stringent genetic biocontainment of yeast with a protein stability switch

Synthetic biology holds immense promise to tackle key problems in resource use, environmental remediation, and human health care. However, comprehensive safety measures are lacking to employ engineered microorganisms in open-environment applications. Genetically encoded biocontainment systems may solve this issue. Here, we describe such a system based on conditional stability of essential proteins. We used a destabilizing domain degron stabilized by estradiol addition (ERdd). We ERdd-tagged 775 essential genes and screened for strains with estradiol dependent growth. Three genes, SPC110, DIS3 and RRP46, were found to be particularly suitable targets. Respective strains showed no growth defect in the presence of estradiol and strong growth inhibition in its absence. SPC110-ERdd offered the most stringent containment, with an escape frequency of <5×10−7. Removal of its C-terminal domain decreased the escape frequency further to <10−8. Being based on conditional protein stability, the presented approach is mechanistically orthogonal to previously reported genetic biocontainment systems.

Design and investigation of a capacitance-coupling pre-ionized sharpening switch.

The sharpening switch is one of the most important elements in the trigger generator, which is used to sharpen the front of the trigger pulse. The breakdown performance of the sharpening switch has an important influence on the output and stability of the trigger generator. In this paper, a novel 200kV capacitance-coupling pre-ionized sharpening switch, which can realize pre-ionization by dividing voltage through its own structural capacitances, is proposed and investigated. In order to obtain the optimal parameters of the pre-ionized sharpening switch, the influences of the electrode structure, electrode material, main gap distance, and pre-ionized gap distance on the breakdown performance are studied experimentally. The experimental results show that the electrode structure with a circular knife-edged cathode and a plate-shaped anode has the smallest breakdown jitter, followed by the needle-plate structure and the tapered ball-head structure. The stainless steel electrode has the smallest jitter, followed by graphite, aluminum, and brass electrodes. When the gap distances of the main gap and the pre-ionized gap are 13 and 1.5mm, respectively, the breakdown stability of the pre-ionized sharpening switch is the best. Under an input voltage pulse with a rise time of about one microsecond, the jitter of the capacitance-coupling pre-ionized sharpening switch with the optimal parameters is 6.08ns, which is about 0.6% of the rise time of the input pulse. The jitter decreases by 44.5% compared to the switch without pre-ionization. The rise time of the output pulse is sharpened to 17ns, corresponding to a voltage rise rate of more than 11 kV/ns.

Phase‐Field Study of Nanocavity‐Assisted Mechanical Switching in PbTiO3 Thin Films

AbstractFerroelectric thin films hold significant promise in various nanoelectronic applications, demanding precise control over their domain structures. While electrical field‐driven polarization switching is currently employed, it often leads to undesirable side effects. In contrast, mechanical switching offers a voltage‐free alternative but faces challenges in thicker films. Recent breakthroughs have demonstrated stable mechanical switching in films up to 200 nm thick, attributed to the presence of nanocavities. These nanoscale voids are believed to facilitate domain transitions, serving as essential pinning centers. In this study, mechanical domain switching in thick ferroelectric films is investigated using phase‐field modeling, with a specific focus on evaluating the influence of nanocavities on domain stability. The effects of cavity parameters (size, depth, and dielectric properties) on mechanical switching stability under various applied pressures are systematically examined. The findings reveal the intricate interplay between these factors and outline the conditions for stable mechanical switching. Furthermore, phase‐field simulations are employed to showcase the energetic mechanisms governing nanocavity‐assisted mechanical switching, while also highlighting the pivotal role of these defects as pinning centers. This investigation elucidates the nanocavity‐assisted mechanical control of polarization and the potential for optimizing thin film design through nanocavity engineering, thus enabling mechanical switching across substantial film thicknesses.

High-Performance Flexible Broadband Photoelectrochemical Photodetector Based on Molybdenum Telluride.

Flexible broadband photodetectors are desired but challenging to be fabricated for next-generation wearable intelligent optoelectronic devices. Considering the narrow bandgap and strong light absorption, molybdenum telluride (MoTe2) based photoelectrochemical photodetectors are successfully assembled by liquid phase exfoliation accompanied with the electrophoretic deposited method. This MoTe2-based photodetector shows a broadband detection in ultraviolet-near-infrared band, long-term stability within 18000s, and fast response in millisecond-level (response time≈19ms, recovery time≈26ms). More importantly, even though the MoTe2 photodetector is bent and twisted at a high degree for several hundred times, it still shows excellent flexibility with stable on-off switching characteristics. Additionally, this photodetector displays a good response for rotation angles in the range from 0° to 360°, and the extracted Iph maintain almost the same value approximately 0.97µAcm-2, suggesting an omnidirectional detection capability. This work demonstrates the proposed flexible photoanode shows a great potential in future broadband omnidirectional detection systems.