Low-voltage Devices Research Articles

Kinetic Study of Oxidation of Ag-Sn-Zn Solid Solution Powders via Hot Mechanochemical Processing.

Ag-based electrical contact materials are essential in low-voltage devices such as relays, switches, circuit breakers, and contactors. Historically, Ag-CdO composites have been preferred due to their superior electrical and thermal conductivities, resistance to arcing, and mechanical strength. However, the toxicity of Cd has led to increased restrictions on its use. With the aim of contributing to the development of a new environment-friendly, Ag-Zn2SnO4-based electrical contact material, the kinetics of the hot mechanochemical oxidation of a Ag-Sn-Zn solid solution obtained by mechanical alloying were investigated. The results indicated that the proposed synthesis route produces Ag-based composites with a homogeneous distribution of nanoscale Zn2SnO4 precipitates, which is unattainable through conventional material processing methods. This kinetic study established that the mechanochemical oxidation of the Ag-Sn-Zn solid solution follows the Johnson-Mehl-Avrami-Kolmogorov model. An analysis of the microstructure and the relationship between the activation energy "Ea" and the Avrami exponent "n" from experimental data fitting suggests that the primary mechanism for the oxidation of the Ag-Sn-Zn solid solution during the hot mechanochemical process is related to the three-dimensional oxide growth being limited by oxygen diffusion after its immediate initial nucleation.

Copper-Nickel/SiC composites for applications on contact electrodes

Novel copper-nickel matrix composites reinforced with silicon carbide (SiC) micro particles for metal contact applications were manufactured by powder metallurgy technology and were experimentally characterized. Cu and Cu alloys are commonly used as metal contact for either vacuum, oil, or SF6 in low-voltage circuit breaker devices, but their application in environments with the presence of oxygen is limited due to their tendency to form high-resistance copper oxides. Thus, the addition of Ni as an alloying element provides resistance to both humidity and several corrosive environments and increases the composites' hardness, mechanical strength, and wear resistance. Moreover, SiC was chosen due to its contribution to mechanical strength, mouldability, low production cost, and non-reactive nature at ordinary temperatures. Here, three SiC particle size distributions were considered, and it was found that the composites' physical properties are also dependent on the ceramic loading. After evaluating these properties, two specific SiC concentrations were potentially considered for electrode applications: 10 wt% and 20 wt%. The obtained hardness values are in the range of 55 – 65 HR30T which guarantees the necessary strength without detriment of the contact area whereas the welding is minimized. In addition to a homogeneous particle distribution in the solid material, specific wear resistance of ∼10-5 mm3N-1m-1 and electrical conductivities of ∼20 %IACS were obtained. Considering these parameters, Cu-Ni/SiC composites' performance is not compromised compared to commercial Ag/WC materials commonly used in metal contact applications.

Simple Voltage Balancing Control of Four-Level Inverter

Multilevel inverters with improved voltage quality are widely used in applications such as motor control and electric vehicles. The four-level active neutral point clamped (4L-ANPC) inverter effectively meets the demands for high power density and low device voltage stress. However, balancing the capacitor voltage and reducing its low-frequency voltage fluctuation are critical challenges that need to be addressed. To address these challenges, this paper proposes a “variable reference + zero-sequence injection” method that requires only three reference voltage signals to determine the injected zero-sequence components. Particularly, the expression of the midpoint current, regarding the modulation index and phase current amplitude, is theoretically derived. This reveals the fundamental connection between the zero-sequence voltage signal and the midpoint current, providing a theoretical foundation for the zero-sequence injection method in four-level inverters. Subsequently, a simulation model and an experimental platform of the 4L-ANPC inverter were developed to compare and analyze the waveforms of the upper and lower capacitor voltages, phase currents, and line voltages under different modulation methods. Additionally, the upper and lower capacitor voltage waveforms were examined for various modulation indices. The results indicate that as the modulation index increases, the low-frequency voltage fluctuation in the upper and lower capacitor voltages also rises. At a modulation index of 0.95, the “variable reference + zero-sequence injection” method effectively suppresses the fluctuation in the upper and lower capacitor voltages to be no more than 1 V. These experimental findings validate the effectiveness of the proposed method.

Demonstration of VGAA-TFETs using InAs/Si Heterojunction on SOI substrate

Tunnel field-effect transistors (TFETs) are expected to be used as a next-generation low-voltage switching device. The TFETs can lower the subthreshold slope (SS) below the physical limit (SS = 60 mV/dec at room temperature) in conventional MOSFETs. Here we demonstrated InAs nanowire (NW)/Si heterojunction vertical gate-all-around (VGAA) TFETs on silicon-on-insulator (SOI) (111) substrates toward vertical integrated circuit applications. The vertical InAs NW channels were grown by selective-area growth on thin SOI(111) substrates.

Experimental analysis of particle dynamics influenced by cavitation bubbles near a rigid wall

This study utilized experimental methods involving high-speed cameras to observe the interaction between cavitation bubbles, generated by a low-voltage electric spark device, and particles near a rigid wall. The dynamic characteristics of the particles were analyzed under varying conditions, including different cavitation bubble sizes, particle sizes, and distances between the cavitation bubble and the wall. Two characteristic parameters were introduced: χ for the particle and cavitation bubble sizes, and λ for the cavitation bubble wall distance. Qualitative distinctions were made among types of particle–bubble interactions, and force analysis was conducted under conditions where χ exceeded the threshold χt. The findings reveal that when χ < χt, particle motion is primarily influenced by the jet effects produced by the cavitation bubble. Conversely, when χ > χt, particle motion is dominated by the radiation forces exerted by the cavitation bubble. Under jet-dominated conditions, particle trajectories were observed to be erratic and unpredictable. For cases where λ < 0, the high-speed jet directly impacts the particle. Conversely, for λ > 0, the jet's velocity decays rapidly upon reaching the particle. In scenarios dominated by radiation forces, the cavitation bubble drew particles away from the wall, followed by their free fall back toward it. The influence of gravity, buoyancy, bubble radiation force, fluid resistance, and virtual mass force on particles was studied when radiation forces prevailed. The acceleration formula for particles was derived through the application of the bubble dynamics equation and was refined based on experimental observations.

Broad temperature range ferrielectric liquid crystal: Temperature dependencies of dielectric and electro-optical properties

Broad temperature range ferrielectric liquid crystal mixture FerriLCM-1 was previously developed in 2022 (Pozhidaev et al. 2022). In that work dielectric and electro-optical properties of the mixture were studied at room temperature. Electrically induced birefringence index reached 0.01 at a wavelength of 532 nm with response times of 300 μs. In this paper we continue the FerriLCM-1 properties investigation in a wide temperature range from the room ones till the isotropic phase transition temperature. It is found that one of the critical electric fields is almost temperature independent, while the Kerr coefficient of quadratic electro-optical effect in deformed helix ferroelectric (DHF) mode grows with temperature increase. This leads to an increase in the depth of phase modulation. Another critical electric field decreases smoothly with temperature rising. At 47–50 °C two critical electric fields merge, while temperature dependencies of all other dielectric and electro-optical parameters of the mixture are continuous and smooth functions. At about 50 °C the maximum electrically induced birefringence in DHF-mode is ΔneffE=0.022 under the applied electric field E=0.4 V/μm and with 80 μs response time. FerriLCM-1 mixture operating in the DHF-mode exhibits a giant Kerr coefficient of 1700 nm/V2 (or even up to 2900 nm/V2 at λ=400nm) at the temperature of 85 °C combined with a 50 μs response time. This is the highest value of Kkerr coefficient among liquid crystals. All these properties make ferrielectric liquid crystal mixture FerriLCM-1 suitable for solving various problems of phase modulation of light and use in low-voltage devices.

Ultralow-Energy-Consumption Photosynaptic Transistor Utilizing Conjugated Polymers/Perovskite Quantum Dots Nanocomposites With Ligand Density Optimization.

The photosynaptic transistor stands as a promising contender for overcoming the von Neumann bottleneck in the realm of photo-communication. In this context, photonic synaptic transistors is developed through a straightforward solution process, employing an organic semiconducting polymer with pendant-naphthalene-containing side chains (PDPPNA) in combination with ligand-density-engineered CsPbBr3 perovskite quantum dots (PQDs). This fabrication approach allows the devices to emulate fundamental synaptic behaviors, encompassing excitatory postsynaptic current, paired-pulse facilitation, the transition from short-to-long-term memory, and the concept of "learning experience." Notably, the phototransistor, incorporating the blend of the PDPPNA and CsPbBr3 PQDs washed with ethyl acetate, achieved an exceptional memory ratio of 104. Simultaneously, the same device exhibited an impressive paired-pulse facilitation ratio of 223% at a moderate operating voltage of -4V and an extraordinarily low energy consumption of 0.215 aJ at an ultralow operating voltage of -0.1mV. Consequently, these low-voltage synaptic devices, constructed with a pendant side-chain engineering of organic semiconductors and a ligand density engineering of PQDs through a simple fabrication process, exhibit substantial potential for replicating the visual memory capabilities of the human brain.

Interaction between cavitation bubbles and plastrons on superhydrophobic surfaces

The interaction between cavitation bubbles and plastrons on superhydrophobic surfaces was investigated using a low-voltage discharge device and high-speed photography techniques. The plastron adhered to the superhydrophobic surface acts as a liquid–gas interface, giving the boundary the ability to repel cavitation bubbles. The direction of bubble collapse is determined by the vector synthesis of the Bjerknes repulsive force from the plastron and the Bjerknes attractive force from the rigid wall when the bubble collapses for the first time. Various collapse behaviors were observed, including bubbles moving away from the plastron, bubbles orienting towards the plastron, and bubbles splitting into sub-bubbles in opposite directions. During the subsequent evolution of the bubbles, the expansion of the plastron led to the reversal of the downward jet or reduced the impact velocity of the jet. Seven jet patterns were identified based on the evolution of the cavitation bubble. Starting from the impact velocity of the jet, three jet patterns, namely, the jet away from the plastron (JA), the funnel-shaped jet away from the plastron (JAF), and the funnel-shaped jet away from the plastron with vortex shedding (JAFV), were found to have a weaker effect on the boundary. Three criteria for the design of plastrons on superhydrophobic surfaces were established: VP>0.25Vmax, HP>0.55Rmax, DP>1.2Rmax. Passive pulsation of the plastron in response to the cavitation bubble exhibited similar behaviors across seven jet patterns except for the JAF pattern: torus-shaped, dish-shaped, and skirt-shaped. The dimensionless wall distance, volume ratio, and plastron morphology parameters were identified as significant factors influencing the interaction between cavitation bubbles and the plastron.

Reversal of the electric field and the anode fall in DC arcs in air during contact opening

A unified one-dimensional model of an arc plasma in air, between copper electrodes, that includes the change of the gap distance is presented. The occurrence of multiple reversals of the electric field and the anode voltage drop is observed. The evolution of the spatial distribution of the electron and heavy particle temperatures with the gap distance and the opening speed is also studied. The model quantitatively predicts a number of plasma properties under conditions that are relevant to the contact separation in low-voltage switching devices.

Bio-inspired multimodal learning with organic neuromorphic electronics for behavioral conditioning in robotics

Biological systems interact directly with the environment and learn by receiving multimodal feedback via sensory stimuli that shape the formation of internal neuronal representations. Drawing inspiration from biological concepts such as exploration and sensory processing that eventually lead to behavioral conditioning, we present a robotic system handling objects through multimodal learning. A small-scale organic neuromorphic circuit locally integrates and adaptively processes multimodal sensory stimuli, enabling the robot to interact intelligently with its surroundings. The real-time handling of sensory stimuli via low-voltage organic neuromorphic devices with synaptic functionality forms multimodal associative connections that lead to behavioral conditioning, and thus the robot learns to avoid potentially dangerous objects. This work demonstrates that adaptive neuro-inspired circuitry with multifunctional organic materials, can accommodate locally efficient bio-inspired learning for advancing intelligent robotics.

Multifunctional wearable Spider-Silk Inspired fabric for personal protection in extreme environments

Personal protective equipment (PPE) plays a vital role in healthcare, industry, and military settings, offering essential protection against various environmental hazards. However, the growing environmental challenges and demand for multifunctional integration make developing PPE that outperforms traditional single-function equipment a significant challenge. Herein, we present a flexible and wearable sandwich-structured film, fabricated by integrating an MXene core layer with Gd(OH)3/TPU outer layers through electrospinning and vacuum filtration process, simultaneously offering neutron and electromagnetic interference (EMI) shielding, energy harvesting, and thermal management. Mimicking spider silk's crystalline and amorphous regions, the outer layers integrate Gd(OH)3 nanorods into TPU nanofibers, thereby enhancing hydrogen bonding and achieving a high tensile strength of 22.94 MPa. Extensive hydrogen-bonding interactions firmly bind the MXene conductive core layer to the gadolinium-rich magnetic outer layers, providing excellent neutron (μ = 22.95 cm−1) and EMI shielding (SE = 35.1 dB). Additionally, the film also functions as a triboelectric nanogenerator (TENG), capturing kinetic energy to power low-voltage electronic devices, reducing reliance on external power in harsh settings. Remarkably, its superior Joule heating capability rapidly reaches various temperature (up to 78.5 ℃) by regulating external voltage to meet diverse user requirements. This study paves the way for future advancements in the realm of multifunctional PPE.

Thermoelectric properties of undoped and Bi-doped GeS monolayers: A first-principles study

Different from the extensive experimental investigations into the thermoelectric (TE) properties of the bulk IV–VI compounds, less attention has been paid to the TE properties of the monolayer IV–VI compounds. Here, we consider the TE transport properties including the Seebeck coefficient, electronic conductance, thermal conductance, power factor, and figure of merit ZT of the undoped and Bi-doped GeS monolayers. Our results show that for both the undoped and Bi-doped monolayers the anisotropy is widely observed in all their TE properties, and the maximum ZT at a certain temperature along the armchair direction is much greater than that along the zigzag direction. Moreover, Bi doping can lead to an increase of the maximum ZT, and there are more ZT peaks appearing near the zero chemical potential. This indicates that the Bi-doped GeS monolayer can work as a TE material at a lower bias voltage, and especially along the armchair direction it can work at zero bias voltage, which obviously strengthens the reliability of the TE devices. As the temperature increases, the maximum ZT will be uniformally increased along the armchair and zigzag directions for both the undoped and Bi-doped GeS monolayers. In the temperature scope from 300 to 800 K, the maximum ZT along the armchair direction of the Bi-doped GeS monolayer will increase from 3.39 to 4.85, which indicates that this Bi-doped GeS monolayer is a promising TE material in a wide-temperature zone. As an application, we have designed the GeS-based TE couples and found that their efficiencies can be greater than 27% at large temperature differences. This research should be an important guidance for designing a low-voltage, wide-temperature-scope, and high-stability TE device.

An Integrated Approach to the Study of the Functional Parameters of Low-Voltage Switching Devices

An Integrated Approach to the Study of the Functional Parameters of Low-Voltage Switching Devices

Study on Optimization of Low-Voltage Multi-Port Flexible Interconnection Device in AC/DC Hybrid Distribution

At present, the back-to-back multilevel modular converter (BTB-MMC) used in low and medium voltage flexible interconnection projects has the disadvantages of high cost and large footprint. Based on MMC, a multi-port flexible interconnection device for AC/DC hybrid distribution network is designed. Firstly, the topology structure and power regulation principle of the device are described by constructing the model of the low and medium port multi-port flexible device. Secondly, an improved inverter model based on independent center line module is proposed, and a multi-objective optimization compensation strategy for multi-function grid-connected inverters is proposed, which effectively improves the ability of independent inverters to carry unbalanced loads and optimizes power quality. Finally, a set of 750 V/50 kW experimental prototype is built, and the performance of the prototype is tested to verify the advantages of the voltage stability of the device.

A low-voltage alternant direct current electroporation chip for ultrafast releasing the genome DNA of Helicobacter pylori bacterium.

Nucleic acid detection, as an important molecular diagnostic method, is widely used in bacterial identification, disease diagnosis. For detecting the nucleic acid of bacteria, the prerequisite is to release nucleic acids inside the bacteria. The common means to release nucleic acids is thechemical method, which involves complex processes, is time-consuming, and remains chemical inhibitors. Compared with chemical methods, electroporation as a physical method has the advantages of easy operation, short-time consumption, and chemical reagents free. However, the current works using electroporation often necessitates high-frequency or high-voltage conditions, entailing bulky power devices. Herein, we propose a low-voltage alternant direct current (LADC) electroporation chip and the corresponding miniature device for ultrafast releasing thegenome DNA from Helicobacter pylori (H. pylori)for detection. We connected a micrometer-interdigital electrode in the chip with a 20V portable battery to make the miniature device. Using this low-voltage device, our chip released genome DNA of H. pylori within only 5ms, achieving a cell lysis rate of 99.5%. We further combined this chip with acolorimetric loop-mediated isothermal amplification assay to visually detect H. pylori within ~ 25min at 10CFU/μL. We detected 11 clinical samples using the chip, and the detection results were consistent with those of the clinical standard. The results indicate that the LADC electroporation chip is useful for ultrafast release of genome DNA from bacteria and is expected to promote the development of nucleic acid detection in POCT and other scenarios.

A CASE STUDY ON HIGH POWER COMPENSATOR OF THE POWER GRID IRREGULARITIES FOR INDUSTRIAL APPLIANCES

The paper presents a case study on development of the high power compensator of the power grid irregularities. The compensator is dedicated for sensitive industrial installations protection against dips, sags and short duration interruptions in public power network. The energy for compensation will be stored in bank of high voltage stacked supercapacitors. The development of the new high power medium voltage compensator will be based on experience gained during the realisation in The Electrotechnical Institute Gdansk Branch a similar medium power low voltage device. The study includes: main power converter topology considerations with some preliminary simulation results including harmonic components discussion, the solution to the problem of fast identification of the grid voltage disturbances, the solution to the problem of compensator waveforms synchronization with the grid and the description of the main operational algorithm of the compensator.

Flexible, high temperature resistant and highly efficient E-heating graphene/polyimide film

Carbon/polymer-based flexible electrothermal films, as a Joule heating material with excellent electrothermal properties, good formability, and lightweight, are a very needed material in aircraft wing de-icing systems, flexible electric heating elements, and low-voltage wearable devices. In this study, a series of flexible electrically heated films were successfully prepared using polyimide (PI) as the film-forming substrate and graphene (GE) as the conductive filler. The effects of graphene content on the morphology, microstructure, and electrothermal properties, as well as the mechanical flexibility of the electrothermal films, were systematically investigated. The results showed that the GE/PI electrothermal films not only retained the good electrical conductivity of graphene but also had the excellent mechanical properties and high heat resistance of polyimide. The electric heating film with the addition of 8 wt. % GE can quickly reach 390 °C at 24 V with uniform temperature distribution, and the mass loss at 500 °C is only 0.98 wt. %. A wide range of applications exist in fields such as flexible electric heating elements.

Manipulating Band-to-Band Tunneling Current in Low-Voltage pMOS Devices in BCD Technology: A TCAD and Experimental Investigation

Manipulating Band-to-Band Tunneling Current in Low-Voltage pMOS Devices in BCD Technology: A TCAD and Experimental Investigation

Алгоритмы оценки основных параметров надежности низковольтного оборудования схем цеховых сетей

The article presents the classification of fuses, breakers, circuit breakers and packet switches. The laws of change of probabilistic reliability characteristics of the studied devices, as well as low-voltage cable lines are determined. Types of functions of change of basic reliability parameters are determined and corresponding graphical dependences are shown. The comparison of the obtained results of the values of probability of failure-free operation time with the requirements of GOST and passport data is carried out. The investigated probabilistic parameters of lowvoltage devices and cable lines are checked for compliance with the accepted law of distribution of random variables.

Performance enhancement of aluminium-gated poly(3-hexylthiophene) transistors with polymer electrolyte/PMMA bilayer gate dielectrics

Tremendous progress in device performance has been realized in electrolyte-gated field-effect transistors (FETs). However, due to the formation of oxides at the metal/electrolyte interface, electrochemically stable and corrosion-resistant noble metals (e.g., gold, platinum, or palladium) have been utilized, which makes device fabrication expensive. In this study, we report an enhanced performance in aluminium (Al)-gated poly(3-hexylthiophene) (P3HT) transistors with polymer electrolyte/poly(methyl methacrylate) (PMMA) bilayer gate dielectrics. This cost-effective Al-gated transistor devices with polymer electrolyte/PMMA bilayer dielectrics measured improved operational stability and hole mobility of ∼0.06 cm2 V−1 s−1 at low operating voltage of −15 V compared to the control Al-gated FETs with PMMA dielectric (∼0.03 cm2 V−1 s−1) and Al-gated devices with electrolyte dielectric (∼10−4 cm2 V−1 s−1). The exceptional performance in the FETs with bilayer gate dielectric would be attributed to an improved charge transport and a robust vacuum metalized Al/PMMA interface in contrast to the electrolyte-gated FETs, which was severely influenced by the formation of aluminium oxide layer (Al2O3) at the Al/dielectric interface. This study provides a practical approach for fabricating low-cost, low-voltage, and high-performance FET devices with hybrid polymer electrolyte/PMMA bilayer dielectrics.