Device Concepts Research Articles

Design of an innovative sanitation system for bike-sharing service

The concept of a novel sanitization device specifically designed for helmets used in bike share services is presented in this scientific work. The system uses ozone, a powerful oxidizing agent, to completely remove dust and bacteria from the helmet surface. Throughout the development process, special attention has been paid to the dual initial goals of efficacy in removing dirt and batteries, as well as ease of use related to the device's safety. In fact, today's sharing services are rarely capable of providing adequate disinfection of the tools, which is especially troubling given the most recent years of pandemic caused by Covid-19. The invention of the ozone-based sanitization device addresses the growing concern about hygiene and safety in bike share services. Furthermore, due to its portability and ease of use, the device is a cost-effective and viable solution for use in a variety of settings. A significant contribution to the advancement of sanitization technology and public health is expected with this work.

Normally-off recessed gate β-Ga2O3 MOSHFETs with a modulation-doped heterostructure back-barrier

This study demonstrates enhancement-mode recessed-gate β-Ga2O3 metal–oxide–semiconductor heterojunction field-effect transistors (MOSHFETs) with a combination of the MOS channel and a modulation-doped heterostructure to improve maximum drain current and on-resistance (RON). In this proposed device concept, modulation doping in the heterostructure back-barrier inserted into the MOS channel increases the electron density in the MOS channel while maintaining a normally-off operation. First, 2D simulations of enhancement-mode recessed-gate β-Ga2O3 metal–oxide–semiconductor field-effect transistors (MOSFETs) were performed in a Silvaco ATLAS TCAD environment to calibrate the transfer characteristics with the measured data of the investigated device reported previously. Second, using calibrated physical models and parameters, the transfer and transconductance characteristics, and output and off-state characteristics of the enhancement-mode recessed-gate β-Ga2O3 MOSHFETs were comprehensively investigated. The maximum drain current at VGS = 8 V and VDS = 10 V could be increased up to 32.6 mA mm−1 from 9.1 mA mm−1 with the MOSHFET in comparison with that of the recessed-gate MOSFET. The breakdown voltage increased considerably from 186 V to 226 V for the recessed-gate MOSHFET. The proposed device also showed a lower RON, which decreased from 354 Ω.mm to 214 Ω.mm owing to greater electron accumulation in the channel owing to the introduction of the modulation-doped heterostructure.

Imaging the magnetic nanowire cross section and magnetic ordering within a suspended 3D artificial spin-ice

Artificial spin-ice systems are patterned arrays of magnetic nanoislands arranged into frustrated geometries and provide insight into the physics of ordering and emergence. The majority of these systems have been realized in two-dimensions, mainly due to the ease of fabrication, but with recent developments in advanced nanolithography, three-dimensional artificial spin ice (ASI) structures have become possible, providing a new paradigm in their study. Such artificially engineered 3D systems provide new opportunities in realizing tunable ground states, new domain wall topologies, monopole propagation, and advanced device concepts, such as magnetic racetrack memory. Direct imaging of 3DASI structures with magnetic force microscopy has thus far been key to probing the physics of these systems but is limited in both the depth of measurement and resolution, ultimately restricting measurement to the uppermost layers of the system. In this work, a method is developed to fabricate 3DASI lattices over an aperture using two-photon lithography, thermal evaporation, and oxygen plasma exposure, allowing the probe of element-specific structural and magnetic information using soft x-ray microscopy with x-ray magnetic circular dichroism (XMCD) as magnetic contrast. The suspended polymer–permalloy lattices are found to be stable under repeated soft x-ray exposure. Analysis of the x-ray absorption signal allows the complex cross section of the magnetic nanowires to be reconstructed and demonstrates a crescent-shaped geometry. Measurement of the XMCD images after the application of an in-plane field suggests a decrease in magnetic moment on the lattice surface due to oxidation, while a measurable signal is retained on sub-lattices below the surface.

Emerging Opportunities for Ferroelectric Field‐Effect Transistors: Integration of 2D Materials

AbstractThe rapid development in information technologies necessitates rapid advancements of their supporting hardware. In particular, new computing paradigms are needed to overcome the bottleneck of traditional von Neumann architecture. Bottom‐up innovation, especially at the materials and devices level, has the potential to disrupt existing technologies through their emergent phenomena. As a new type of conceptual device, 2D ferroelectric field‐effect transistor (FeFET) is highly sought after due to its potential integration with modern semiconductor processes. Its low power consumption, area efficiency, and ultra‐fast operation provide an extra edge over traditional technologies. This review highlights recent developments in 2D FeFET, covering their device construction, working mechanisms, 2D ferroelectric polarization mechanism, multi‐functional applications and prospects. In particular, the combination of 2D semiconductor and ferroelectric dielectric materials for multi‐functionality applications is discussed. This includes non‐volatile memories (NVM), neural network computing, non‐volatile logic operation, and photodetectors. As a novel device platform, 2D semiconductor and ferroelectric interfaces are bestowed with a plethora of emergent physical mechanisms and applications.

Monolithic 2D Perovskites Enabled Artificial Photonic Synapses for Neuromorphic Vision Sensors.

Neuromorphic visual sensors (NVS) based on photonic synapses hold a significant promise to emulate the human visual system. However, current photonic synapses rely on exquisite engineering of the complex heterogeneous interface to realize learning and memory functions, resulting in high fabrication cost, reduced reliability, high energy consumption and uncompact architecture, severely limiting the up-scaled manufacture, and on-chip integration. Here a photo-memory fundamental based on ion-exciton coupling is innovated to simplify synaptic structure and minimize energy consumption. Due to the intrinsic organic/inorganic interface within the crystal, the photodetector based on monolithic 2D perovskite exhibits a persistent photocurrent lasting about 90s, enabling versatile synaptic functions. The electrical power consumption per synaptic event is estimated to be≈1.45×10-16J, one order of magnitude lower than that in a natural biological system. Proof-of-concept image preprocessing using the neuromorphic vision sensors enabled by photonic synapse demonstrates 4 times enhancement of classification accuracy. Furthermore, getting rid of the artificial neural network, an expectation-based thresholding model is put forward to mimic the human visual system for facial recognition. This conceptual device unveils a new mechanism to simplify synaptic structure, promising the transformation of the NVS and fostering the emergence of next generation neural networks.

Atypical features of the Austrian model of criminal law protection of circulation of medical devices

The article examines the atypicality of the Austrian model of criminal law protection of the circulation of medical products and medical devices. The authors note that the acts of foreign criminal legislation distinguish types of criminal offenses that encroach on pharmaceutical activity, which to a certain extent coincide with those provided for in the Criminal Code of Ukraine. At the same time, it is the Austrian model of protection of circulation of medical products and medical devices that most successfully, as the analysis of acts of foreign criminal legislation shows, demonstrates the legislator’s approach to the normative and legal regulation of this sphere of circulation.
 The authors note that there are certain factors that influence the atypicality of the Austrian model, namely: a) the legislative definition of the concept of pharmaceutical products, since the content of this concept “legislatively outlines” the limits of criminal protection and affects the mechanism of ensuring this protection; b) determination of the limits of criminal protection of medical devices depending on the requirements of the Austrian Federal Law on Medical Devices (Bundesgesetz betreffend Medizinprodukte) dated October 28, 2021.
 The article focuses on the fact that Austrian legislation provides legal protection of medical devices as a mandatory component of pharmaceutical activity despite the fact that the mentioned Austrian Federal Law on Medical Devices does not contain an independent “exhaustive definition” of the concept of medical devices, as is done, for example, in the German Medical Products Act of Austria (Gesetz uber Medizinprodukte) as amended on August 7, 2002.
 The authors note that the atypicality of the Austrian “model” of criminal protection of medical devices is due to the fact that the Austrian Federal Law on Medical Devices in its § 80 contains provisions on “administrative punishment (Verwaltungsstrafe)” for violation of the established order of circulation of medical products, which (prescriptions ) affect the provision of criminal protection of medical products and its limits.
 The article focuses on the characteristics of the “administrative penalty (Verwaltungsstrafe)” in the system of Austrian law, which is an independent type of measures of an administrative and legal nature.

Resistive Memory-Switching Behavior in Solution-Processed Trans, trans-1,4-bis-(2-(2-naphthyl)-2-(butoxycarbonyl)-vinyl) Benzene-PVA-Composite-Based Aryl Acrylate on ITO-Coated PET.

Resistive switching memories are among the emerging next-generation technologies that are possible candidates for in-memory and neuromorphic computing. In this report, resistive memory-switching behavior in solution-processed trans, trans-1,4-bis-(2-(2-naphthyl)-2-(butoxycarbonyl)-vinyl) benzene-PVA-composite-based aryl acrylate on an ITO-coated PET device was studied. A sandwich configuration was selected, with silver (Ag) serving as a top contact and trans, trans-1,4-bis-(2-(2-naphthyl)-2-(butoxycarbonyl)-vinyl) benzene-PVA-composite-based aryl acrylate and ITO-PET serving as a bottom contact. The current-voltage (I-V) characteristics showed hysteresis behavior and non-zero crossing owing to voltages sweeping from positive to negative and vice versa. The results showed non-zero crossing in the devices' current-voltage (I-V) characteristics due to the nanobattery effect or resistance, capacitive, and inductive effects. The device also displayed a negative differential resistance (NDR) effect. Non-volatile storage was feasible with non-zero crossing due to the exhibition of resistive switching behavior. The sweeping range was -10 V to +10 V. These devices had two distinct states: 'ON' and 'OFF'. The ON/OFF ratios of the devices were 14 and 100 under stable operating conditions. The open-circuit voltages (Voc) and short-circuit currents (Isc) corresponding to memristor operation were explained. The DC endurance was stable. Ohmic conduction and direct tunneling mechanisms with traps explained the charge transport model governing the resistive switching behavior. This work gives insight into data storage in terms of a new conception of electronic devices based on facile and low-temperature processed material composites for emerging computational devices.

Unravelling the nanoscale mechanism of polarization reversal in a Hf0.5Zr0.5O2-based ferroelectric capacitor by vector piezoresponse force microscopy.

Ferroelectricity is in demand in many device concepts in electronics, energy and microsystem engineering. The performance of ferroelectrics-based devices is determined by either out-of-plane or in-plane polarization, or out-of-plane or in-plane piezoelectric strain. Real prospects for the practical implementation of innovative devices opened up after the discovery of ferroelectricity in ultrathin hafnium oxide films, due to their perfect compatibility with silicon technology. Ferroelectric properties of this material have been assigned to an orthorhombic structural phase with a single polar axis, but the spatial orientation of the polarization vector and the tensorial piezoelectric behaviour, which are inextricably coupled, still remain unknown. Herein, the rotation of the polarization vector in a Hf0.5Zr0.5O2 (10 nm) capacitor during polarization switching and the spatial distribution of longitudinal and shear piezoelectric coefficients are elucidated at the nanoscale using operando vector piezoresponse force microscopy. In most of the capacitor, a 180°-flipping of the polarization vector is observed, which is consistent with the orthorhombic phase structure. However, a rather large fraction of the capacitor is also occupied by nanoregions of ferroelastic (non-180°) switching, which is explained by the effect of the local mechanical stress. To quantify the three-dimensional piezoresponse, a novel approach exploiting the Poisson effect in artificially created non-ferroelectric regions is proposed and it shows that the shear piezoelectric coefficient is twice the longitudinal coefficient. The experimental insights entail an important step in fundamental understanding of the ferroelectric and piezoelectric properties of hafnium oxide and have great potential to trigger new versions of ferroelectric-based devices.

Exploring the cell interactome: deciphering relative impacts of cell-cell communication in cell co-culture using a novel microfluidic device.

The human body is made up of approximately 40 trillion cells in close contact, with the cellular density of individual tissues varying from 1 million to 1 billion cells per cubic centimetre. Interactions between different cell types (termed heterotypic) are thus common in vivo. Communication between cells can take the form of direct cell-cell contact mediated by plasma membrane proteins or through paracrine signalling mediated through the release, diffusion, and receipt of soluble factors. There is currently no systematic method to investigate the relative contributions of these mechanisms to cell behaviour. In this paper, we detail the conception, development and validation of a microfluidic device that allows cell-cell contact and paracrine signalling in defined areas and over a variety of biologically relevant length scales, referred to as the interactome-device or 'I-device'. Importantly, by intrinsic device design features, cells in different regions in the device are exposed to four different interaction types, including a) no heterotypic cell interaction, b) only paracrine signalling, c) only cell-cell direct contact, or d) both forms of interaction (paracrine and cell-cell direct contact) together. The device design was validated by both mathematical modelling and experiments. Perfused stem cell culture over the medium term and the formation of direct contact between cells in the culture chambers was confirmed. The I-device offers significant flexibility, being able to be applied to any combination of adherent cells to determine the relative contributions of different communication mechanisms to cellular outcomes.

Neuron Foundry Mach 8: A Concept of Multi-modal Neuro-supportive Energy Therapy Device for Treating Neurodegenerative Disorders

The prevalence of neurodegenerative disorders is rising as the population ages, and many ailments, such as depression, Parkinson’s disease, Alzheimer’s disease, autism spectrum disorder, and multiple sclerosis, have intricate underlying mechanisms that are still poorly understood. The Neuron Foundry Mach 8 is a multi-modal neuro-supportive energy therapy device designed to treat neurodegenerative disorders through daily sessions. This device proposes to deliver safe and controlled energy therapy through multiple therapeutic pathways, including stimulating brain mitochondrial energy, supporting homeostasis within the brain’s immune system, increasing melatonin production within neuronal mitochondria, and triggering cellular communication through the brain’s white matter. By combining these unique energy-based treatments, this device holds promising potential for slowing, stopping, reversing, or at least reducing the effects of neurodegenerative diseases.

Design of Ultra-High Density Archival Storage Memory with Nanoprobe and Patterned Oxygenated Amorphous Carbon with Metal Nanoclusters

Recent prosperity of artificial intelligence is undoubtedly making global data increase at a phenomenal rate. This obviously poses more stringent requirements on current storage devices. Unfortunately, considerable effort is only devoted to the development of on-chip storage device, while off-chip storage technology, particularly for archival storage device, remains slowly progressed. To further innovate the archival storage device, and thus revive its market, we here proposed a novel concept of an archival storage device based on scanning nanoprobe and oxygenated amorphous carbon having metal nanoclusters. A comprehensive numerical model was developed to mimic the write and readout performances of such archival storage device. It was found that the introduction of metal nanoclusters induced much stronger electric field inside the amorphous carbon layer than the case without metal nanoclusters. This beneficially facilitated the growth of conductive filament along metal nanoclusters, and the feasibility of using the proposed device to achieve an areal density of terabit per-square-inch area density, a write energy of picojoule energy per bit, and a switching speed of tens of nanoseconds, was demonstrated.

Emulation of neuron and synaptic functions in spin-orbit torque domain wall devices.

Neuromorphic computing (NC) architecture has shown its suitability for energy-efficient computation. Amongst several systems, spin-orbit torque (SOT) based domain wall (DW) devices are one of the most energy-efficient contenders for NC. To realize spin-based NC architecture, the computing elements such as synthetic neurons and synapses need to be developed. However, there are very few experimental investigations on DW neurons and synapses. The present study demonstrates the energy-efficient operations of neurons and synapses by using novel reading and writing strategies. We have used a W/CoFeB-based energy-efficient SOT mechanism to drive the DWs at low current densities. We have used the concept of meander devices for achieving synaptic functions. By doing this, we have achieved 9 different resistive states in experiments. We have experimentally demonstrated the functional spike and step neurons. Additionally, we have engineered the anomalous Hall bars by incorporating several pairs, in comparison to conventional Hall crosses, to increase the sensitivity as well as signal-to-noise ratio (SNR). We have performed micromagnetic simulations and transport measurements to demonstrate the above-mentioned functionalities.

Sub-micron Assembly Alignment Detection Method and System Based on Optical Diffraction

With the continuous development of manufacturing technology, precision instruments are increasingly moving towards miniaturization, precision, and integration. The assembly accuracy of the product has become a critical factor that limits the performance of the product. Assembly alignment is a significant part of the assembly process, and the accuracy of alignment detection has a significant effect on the final assembly accuracy of the product. Currently, the mainstream technology is to recognize and detect the final image of two parts using microscopic visual inspection technology. However, this method struggles to achieve sub-micron level alignment detection accuracy. In this paper, we presented a sub-micron alignment detection system based on optical diffraction, and the factors influencing the detection accuracy are analysed. Based on this, an experimental assembly alignment detection system was designed based on piezoelectric ceramic drive, laser confocal sensor monitoring feedback, and the mapping relationship between the nanoscale moving position of the diffraction aperture and the diffraction result to achieve sub-micron displacement detection. In addition, experimental tests have been carried out to verify the feasibility of this program. The experimental results indicate that the developed alignment detection method and system can achieve sub-micron alignment detection accuracy, providing a novel device and development concept for high-precision assembly alignment detection.

IoT Educational Framework Case Study: Devices as Things for Hands-on Collaboration

Abstract— As IoT continues to reshape industries and daily life, our research revolves around cultivating a generation of IoTliterate individuals capable of addressing today’s challenges. In the Internet of Things (IoT) education, it is crucial to provide students with the ability to work with the technology and apply it to real-world problems. This creates a demand for teaching methodologies compatible with newly explored networked learning activities, for example, Challenge-Based Education (CBE). This study explores the IoTempower Framework, a versatile pedagogical tool dedicated to enhancing IoT CBE education. Its open-source nature and teaching support make it accessible and adaptable for IoT courses that support hands-on learning and teaching practices. This paper investigates IoTempower Framework's educational applications by analyzing three higher-education study cases where it was deployed. It explores the framework with its associated devices as tools for experiential collective and critical learning. Through a survey of students and participatory observations, the paper evaluates the framework's impact on fostering collaborative engagement in project-driven courses. It introduces the concept of devices as social-material entities or design things and how this approach to device development can aid collaborative teaching and learning experiences. The paper underscores IoTempower Framework as a social-material tool that is significant in shaping effective IoT education by highlighting the interplay between technical and social aspects of its devices as pedagogical tools. Keywords— Internet of Things; Education; IoT Framework; Devices; Design Things; Collaboration.

Light management for ever-thinner photovoltaics: A tutorial review

Ultra-thin solar cells, an order of magnitude thinner than conventional technologies, are an emerging device concept that enables low-cost, flexible, lightweight, and defect-tolerant photovoltaics. However, the advent of ultra-thin technologies is hindered by the fundamental challenge of poor light harvesting in thinnest absorber layers, which entails prohibitive photocurrent and efficiency penalties. Here, from a tutorial perspective, we review different light-management platforms that can overcome this inherent limitation, namely, antireflection coatings, rear mirrors, and light-trapping textures. We then review the state-of-the-art performances that have been achieved with these strategies and that have led to records of ∼20% efficiency in ∼200 nm absorbers. Finally, we identify persisting challenges and potential development avenues for attaining competitive performance with ever-thinner photovoltaic devices.

Communicative activity in teaching professionally oriented English: a methodological aspect

New conditions determine new requirements to the quality of specialists’ training for professional activity. It is necessary to emphasize the important role of communicative activity development in professional-personal direction. The purpose of this article ― to systematize the results obtained in the framework of pedagogical research conducted on the basis of Aktobe Regional University named after K. Zhubanov, with the 3 rd year students of the specialty “5B010200 ― “Pedagogy and Methods of Primary Education”” with the Kazakh language of training. Scientific importance is designated by means of allocation of theoretical and conceptual device, practical importance consists in the chosen and tested complex of diagnostics, and techniques on communicative activity. The methodology of research is based on activity (A. N. Leontiev, V. A. Slastenin, etc.) and acmeological (N. V. Kuzmina, etc.) approaches, review-analytical and diagnostic research methods. The main results of the study were the systematization of the identified components of communicative activity, methods and techniques for teaching foreign language to students of non-linguistic specialties. The value is the cultural enrichment of the student on the basis of competently selected teaching material. The practical value of the results of the work is based on methodological recommendations to university faculty working in this area.

Output performance improvement for thermoelectric transistor with the consideration of the Thomson effect and geometry optimization

Despite significant attention paid to thermoelectric generators in the energy conversion field, their limited output performance has restricted their large-scale applications. Therefore, there is a pressing need to conceive a novel thermoelectric device concept that can strengthen their competitiveness. In this context, the concept and principle of thermoelectric (TE) transistor with ultrahigh performance is a demand-driven innovation. Built on the foundation of a PNP structure, TE transistor only relies on the Seebeck voltage to operate normally. This work employs P-type Bi0.5Sb1.5Te3 and N-type Bi2Te2.97Se0.03 as the component materials. By considering the conduction heat, Joule heat, Thomson heat, and temperature-dependent material properties, a one-dimensional heat transfer model was used to obtain the nonlinear temperature profile inside TE transistor. Further, the structure and operation conditions of TE transistor with varying geometric dimensions were determined based on the hole concentration distribution and build-in voltage variation. Finally, the optimal concentrations and geometric dimensions of TE transistor were obtained using a compromise method. The calculation results reveal that TE transistor can achieve an optimal output power of 133.7 mW under a temperature difference of 50 K (Th = 353 K, Tc = 303 K) with the corresponding conversion efficiency of 7.73%. This work provides theoretical guidance for future experimental validation of TE transistor.

(Invited) Integration of Functional Nanostructures and Nanoparticles into Micro- and Nanoelectronic Components and Systems

In recent decades, there has been a significant evolution of microelectronic and semiconductor technologies towards the nanoscale. Both bottom-up and top-down integration concepts of functional nanostructures and nanoparticles into micro- and nanofabricated electronic components have become critical issues that decisively affect the performance of smart electronic systems in various application areas such as environmental sensing and energy harvesting.Functional nanostructures and nanoparticles of different shapes, sizes, morphologies, and materials are now used in various technical and industrial applications, medicine, pharmacy, biology, electronics, power engineering, ecology, and many other fields. However, the complex engineering challenge here is the integration of functional nanostructures, such as molecular components (e.g., functional self-assembled molecular monolayers or entities of desoxyribonucleic acid, DNA), organic or inorganic nanoparticles (metal, semiconductor, colloidal materials), or similar building blocks into nanolithographically fabricated environments.Manufacturing paradigms for this integration go beyond current CMOS- and MEMS-fabrication schemes. Scale-bridging and hybrid manufacturing schemes that combine established top-down manufacturing techniques for microelectronic devices, including aspects of nanotechnology, with bottom-up nanoassembly of molecules on unstructured and pre-structured substrates are required. Microsystems technology based on the combination of conventional semiconductor processing with biotechnological approaches has thus become an emerging field with manifold applications, especially in the field of sensor technology.This contribution describes two illustrative and innovative research questions in nanopatterning and system integration at the micro-nano-interface to motivate applications with new and unprecedented functionalities. The first research question focuses on network-based biocomputing (NBC) using biological agents driven by biomolecular motor proteins in a lithographically fabricated nanofluidic channel system. This approach opens up opportunities for energy-efficient solutions to complex mathematical problems as they make their way through the NBC network. Methods are required to create switchable and rewritable nano-networks to address different mathematical problems using a single NBC-chip. Therefore, stimuli-responsive materials must be selectively and locally deposited into the nano-network to control the transport of the filaments through the network.The second research question focuses on nanophotonic devices based on DNA origami. The high-precision arrangement of nanoscopic substructures using specific binding sites (capture ends) of the DNA origami enables the precise arrangement of DNA origami functionalized with individualized metal nanoparticles. This arrangement could be used to exploit individual spectral response mediated by plasmonic effects.From a technological perspective, top-down lithographic nanostructuring technologies and bottom-up nanostructuring technologies are the basis for new device concepts. The adaptability of nanostructures to the world of biological molecules and other nanoscopic building blocks such as quantum dots and nanoparticles enables novel, even personalized, devices and engineering solutions.

Half‐Valley Ohmic Contact: Contact‐Limited Valley‐Contrasting Current Injection

AbstractThe 2D ferrovalley semiconductor (FVSC) with spontaneous valley polarization offers an exciting material platform for probing Berry phase physics. How FVSC can be incorporated in valleytronic device applications, however, remain an open question. Here, the concept of metal/semiconductor (MS) contact into the realm of valleytronics is generalized. A half‐valley Ohmic contact is proposed based on FVSC/graphene heterostructure, where the two valleys of FVSC separately forms Ohmic and Schottky contacts with those of graphene, thus allowing current to be valley‐selectively injected through the ‘Ohmic’ valley while being blocked in the ‘Schottky’ valley. A theory of contact‐limited valley‐contrasting current injection is developed and such transport mechanism can produce gate‐tunable valley‐polarized injection current. Using RuCl2/graphene heterostructure as an example, a device concept of valleytronic barristor is illustrated, where high valley polarization efficiency and sizable current on/off ratio, can be achieved under experimentally feasible electrostatic gating conditions. These findings uncover contact‐limited valley‐contrasting current injection as an efficient mechanism for valley polarization manipulation, and reveals the potential of valleytronic MS contact as a functional building block of valleytronic device technology.

Design of a memristor-based neuron for spiking neural networks

The primary objective of neuromorphic system design is to surpass limitations in energy efficiency and scaling of classical von Neumann computing systems, through the emulation of animals’ nervous systems. This is achieved by conducting calculations in memory and encoding information in impulse signals, ultimately leading to enhanced adaptability. Adhering to these principles allows for improved energy efficiency and computational speed when solving machine learning problems, encompassing biomedical applications, embedded systems, and cyber-physical systems. Functional blocks modeling the main elements of the central nervous system, namely neurons and synapses, offer an advantage in implementing learning on a chip. The use of memristive electronic components, capable of altering their resistance based on the charge flowing through them, opens new doors for hardware implementation of neuromorphic systems. These devices offer advantages over conventional transistor electronics with respect to power consumption, component density, and performance. To achieve optimal results, the architecture of neuromorphic systems should be optimized at the device level. Memristive components are utilized to create neurons and synapses. This thesis is specifically focused on producing memristive neuron-like spike signal generators. Previously, memristive neurons were crafted using a locally active element comprised of vanadium dioxide VO2, which incorporated a negative differential resistance section of the IV-curve. One of the recent advancements in this field is a spiking neuron with frequency adaptation [1]. Its drawbacks, however, involve separating the memristive and locally active elements physically, resulting in higher energy consumption and decreased integration quality. In [2], models of memristive neurons with minimal complexity are introduced, which incorporate the Leaky Integrate-and-Fire principle. However, the circuits presented require the application of negative voltage pulses to a DC battery to reset the memristor to its initial high-resistance state. This limitation restricts its sphere of application in neuromorphic systems. This paper proposes a model of a neuron that overcomes these limitations by using the negative differential resistance of the memristor to generate spikes, along with integrating supplementary circuit components to sustain the resistive switching cycles of the memristor. The neuron model under consideration is implemented using the NI Multisim 14.2 SPICE environment and has been verified in the NI LabVIEW 2022 tool environment. The equations of the modified model of the generalized mean metastable switch of the memristor with self-directed channel [3] represent the current in the memristor branch of the neuron equivalent circuit. The simplicity of the equivalent circuitry of the neuron is attained by merging all the nonlinear features necessary for spike generation into one memristor model. The experimental phase of the study employed obtainable memristors from Knowm Corporation and the laboratory prototyping platform NI ELVIS III. The investigation of the proposed neuron model was accomplished through the application of sinusoidal and rectangular input signals. The refractory time of the neuron model was calculated. The chosen stack of computer simulation and semi-natural modeling technologies is applied within the research-driven design concept of electronic devices. This approach considers the importance of refining the properties and identification of the design object or its components during the development cycle.