Critical Performance Parameters Research Articles

Sensitivity enhanced flexible capacitive pressure sensor microstructure optimization for biomedical applications

This paper explores the design and optimization of Flexible Capacitive Pressure Sensors (FCPS) using microfabrication technology for applications in the emerging field of flexible electronics, with a particular focus on measuring bio-signals characterized by lower pressure ranges. Sensitivity, a critical parameter for effective FCPS performance, is investigated through a comprehensive series of simulation analyses employing finite element modeling. The study involves varying geometrical and mechanical parameters that influence FCPS performance, individually adjusting each parameter while keeping others constant. Microstructures such as cuboids, truncated pyramids with an aspect ratio of 0.5, cylinders, pyramids, and cones are modeled on the dielectric material surface. The parameters considered include inter-space, base length, height, and elastic modulus, to enhance FCPS sensitivity and linearity. Among the different shapes modeled, the cone exhibits the highest sensitivity, followed by the pyramid structure. Comparative analysis indicates that the cone and pyramid shapes demonstrate 15- and 10-times higher sensitivity, respectively, compared to the cuboid structure under an applied pressure of 10 Pa. Simulation results suggest that sensitivity can be finely tuned, with higher inter-space and microstructure height, as well as lower base length and Young’s modulus of the dielectric material, contributing to increased sensitivity. However, it is noted that these conditions may lead to decreased capacitance in the absence of applied pressure due to air occupation relative to the dielectric material. The findings are further compared with existing literature, and the FCPS response analysis provides valuable insights for the future design of FCPS, particularly in the context of biomedical applications requiring precise low-pressure signal measurements. This research contributes to advancing the understanding of FCPS performance optimization and lays the groundwork for the development of sensors with enhanced sensitivity for bio-medical applications.

Real-time Finite Element Analysis based on surrogate model

In the field of engineering, Finite Element Analysis (FEA) serves as a pivotal numerical simulation tool. Nevertheless, its inherent offline nature and dependency on real-time data pose limitations on its versatility. To confront this challenge, a real-time FEA approach centered on surrogate modeling has been developed. This method enables the instantaneous prediction of critical performance parameters, thereby providing crucial support for real-time decision-making and process monitoring. In the context of this study, the focus is on the glass compression molding process, a process that is not easily observable. The research commences with preliminary thermal conduction simulations conducted using ABAQUS software. Subsequently, a surrogate model is constructed to facilitate real-time FEA for the temperature field of the glass preform. Finally, Unity 3D software is harnessed for visualization, offering an effective tool for the real-time monitoring and control of the glass-forming process.

Blocker tolerant cascode LNA for Wifi & IoT applications

SummaryWithin the domain of contemporary wireless communication systems, crafting Low‐Noise Amplifiers (LNA) holds a pivotal significance in achieving heightened signal sensitivity and comprehensive system efficacy and suppresses noise contributions from subsequent stages. Additionally, the low noise figure (NF) and high gain are critical LNA performance parameters in portable applications. Normally, LNA contains issues in noise performance, amplification, bandwidth, gain, and stability. To overcome these challenges, there must be a proper selection of transistors, harmonious impedance calibration, bias optimization, and circuit fine‐tuning. Moreover, metal oxide semiconductor field effect transistors (MOSFETs) are a popular choice in LNA design because of their excellent noise performance, high input impedance, complementary metal‐oxide semiconductor (CMOS) integration capabilities, low power operation, and suitability for a wide range of frequency applications. Through simulation and iterative enhancement, the LNA showcases remarkable Noise Figure, amplification, and linearity over a designated frequency span. This creation contributes to the advancement of radio frequency (RF) circuitry by designing an approach for LNA crafting that harmonizes conflicting prerequisites and unveils effective noise mitigation tactics. The outcomes emphasize the importance of a deliberated circuit architecture and parameter adjustment in accomplishing superlative LNA capabilities, rendering it fit for assimilation into diverse communication systems that demand minimal noise and heightened sensitivity.

Double Passivation Using Ultra‐Thin Insulators for Improved Stability and Efficiency of Quasi‐2D Perovskite Light Emitting Diodes

AbstractInterface engineering is a critical parameter for optimal optoelectronic device performance. In quasi‐2D perovskite light emitting diodes (PeLEDs), traditional poly (3,4‐ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) hole injection layer (HIL) is replaced by self‐assembled monolayer (SAM) [2‐(3,6‐dibromo‐9H‐carbazol‐9‐yl) ethyl] phosphonic acid (Br‐2PACz) HIL. The deep highest occupied molecular orbital (HOMO @ −5.73 eV) of Br‐2PACz facilitates the efficient hole‐injection along with a reduction in leakage current by 4–5 orders of magnitude as compared to PEDOT:PSS (HOMO @ −5.00 eV) HIL based optimized PeLEDs. Ultra‐thin SAM‐based Br‐2PACz HIL presents two challenges: i) device reproducibility is hindered by spatial inhomogeneity, and ii) it fails to regulate nonradiative recombination at the perovskite/HIL interface. To address these challenges, the ultra‐thin interlayer of atomic layer deposited aluminum oxide (Al2O3) is utilized between Br‐2PACz, and perovskite which aids in passivating the interfacial states at the HIL/perovskite interface. With the optimized thickness of Al2O3 interlayer (3 nm), the device's external quantum efficiency (EQE) improved from 9.47% to 13.14%, accompanied by luminous efficiency of 42.8 cd A−1. An ultra‐thin interlayer of lithium fluoride (LiF) (2 nm) is implemented on the top side of the perovskite, which can provide 1.5 times increase in the device's LT50 stability.

Direct ink writing of viscous inks in variable gravity regimes using parabolic flights

Additive manufacturing (AM) has significant utility for off-planet fabrication where dedicated infrastructure is severely limited, weight reduction and in situ resource utilization is desirable, and demands for complex systems are high. Direct ink writing (DIW) is a useful AM technique since it enables the deposition of a broad set of materials and the co-printing of multiple materials simultaneously. This allows for the fabrication of complex functional devices and systems in addition to structural objects. To evaluate this technique for space applications, this study characterized DIW in low gravity environments. Parabolic flights were used to simulate Martian, Lunar, and Micro gravity, and the effects that these 3 gravity regimes have on two critical print performance parameters, drooping and slumping, was evaluated using viscous paste inks deposited with an auger-driven extrusion head. In the drooping case, bridging structures were printed across gaps without support material, and the deformation was monitored. In the slumping case, a wall was printed through sequential layer deposition, and the vertical displacement of each layer under reduced gravity was explored. As expected, we found that a reduction in apparent gravity led to a decrease in the droop of a printed line, and as apparent gravitational acceleration is decreased its impact on the magnitude of drooping becomes less significant. For wall structures printed in simulated Lunar or Martian gravity regimes, the total structure height was found to be similar to that of a structure printed under Earth's gravitational conditions. In contrast, for prints performed in microgravity, it was found that slumping was significantly reduced and structure height was larger. These results provide experimental data to enable the design and optimization of appropriate structures and tool paths for printing objects using DIW for off-planet manufacturing.

Development and Evaluation of a MQ-5 Sensor-Based Condition Monitoring System for In-Situ Pipeline Leak Detection

The condition monitoring system for an in-situ pipeline is an innovative concept that uses MQ-5 sensors to detect fuel leaks in pipelines and relay concentration data to a receiver station. The essence of the monitoring process is to ensure the safety and security of engineering properties and lives. The project addresses the crucial requirement for rapid detection of fuel leaks to avoid environmental problems, economic losses, and safety risks connected with pipeline circulation. The goal is to create a leak detection monitoring system. The project required the design and execution of four transmitter stations, each responsible for detecting fuel leaks at various places along a small-scale pipeline and transmitting concentration data to a central receiver station. The system's response time, a critical performance parameter for this project, was measured by timing how long it took for an alert to arrive at the receiving station after the transmitter detected a leak. This time was measured at three distances between the transmitter and receiver stations: 1m, 2m, and 3m. Multiple measurements were taken at each distance, and the average response time was computed. The results showed that as the distance between the stations increased, so did the reaction time. The average response time at 1m was 3.37 seconds, whereas, at 2m and 3m, it was 3.856 seconds and 4.198 seconds, respectively. A t-test inference was performed to check that there was a distinct difference between the response times for each distance, and a significant difference was detected. The built system effectively demonstrated its ability to detect fuel leaks, and the observed response times offered useful information about the system's performance at various distances. This technology demonstrates the potential to improve pipeline transportation safety and efficiency by enabling early identification of fuel leaks.

A gas-driven capillary based on the synergy of the catalytic and photothermal effect of PB@Au for Salmonella typhimurium detection

Rapid detection method for Salmonella typhimurium is vital to prevent the spread of food-borne diseases. In this work, a gas-driven capillary detection method was established to achieve sensitive and rapid detection of Salmonella typhimurium using the catalytic and photothermal synergy of Prussian blue-nanogold (PB@Au) nanomaterials. The immuno-PB@Au probe attached to the capillary by specific identification of target bacteria catalyzed the H2O2 under laser irradiation, driving the H2O2 liquid column to move (ΔL) by producing gas, and achieving the quantitative detection of Salmonella typhimurium. After detailed optimization of the critical performance parameters of the gas-driven capillary assay, the limit of detection (LOD) after laser irradiation and being catalyzed by PB@Au was calculated to be 37 CFU mL−1 through the determination of different concentrations of target bacteria. Furthermore, the detection performances of the gas-driven capillary method were evaluated in detail, and the recoveries ranging from 92.9 ± 4.7 % to 107.7 ± 4.1 % were achieved using the spiked actual samples with complex matrices, indicating that the established rapid assay can offer promising strategies for the monitoring and controlling of food-borne pathogenic bacteria.

Process Modularity Impact on Manufacturing Lead Time and Throughput Rate in Terms of Mass Customization

As mass customization becomes more pervasive in many sectors, researchers need to update traditional approaches to the optimization of critical performance and design parameters in order to help companies in their effort to implement this strategy. In general, implementation of mass customization from a manufacturing perspective is frequently focused on shortening cycle times, reducing production cost, and increasing throughput rate of parts. In this paper, process structure modularity impact on manufacturing lead times and throughput rates is explored. An important precondition to explore these relationships is the awareness that process modularity is conceptualized and quantified in an appropriate way. For this purpose, three independent modularity measures were employed to provide more reliable assessment of this system property. The relationships were investigated on the basis of simulation experiments using deterministic models of alternative process structures. For the purpose of the relationships exploration, two case studies were conducted, theoretical and practical ones. The results from the experiments showed that there are moderate correlations between process modularity and manufacturing lead time (ρ = −0.45), as well as between process modularity and throughput rate (ρ = 0.45).

Melting enhancement of latent heat thermal energy storage by implementing new geometric design

Latent heat thermal energy storage systems can manage peak energy demand with the unique thermo–physical properties of phase change material. However, the primary concern of using these systems is their low heat transfer rate. The present study attempts to increase the thermal performance of these systems using perforated stair fins and changing the enclosure’s geometry. For this purpose, parametric studies have been conducted to assess the effect of perforations on fins with different diameters (from dimensionless diameters of 1 to 2) and different numbers of perforations (from 6 to 24). Next, the effect of changing the enclosure's geometry to a parallelogram, trapezoid, and rectangle is investigated. Finally, by simultaneously applying the above–mentioned ideas, the performance parameters of the system are calculated and compared with the base case (enclosure with simple stair fins). The investigations are conducted using the finite volume method, and the material melting process is carried out based on the enthalpy–porosity method. All the simulations are three–dimensional and transient, with variable properties of material in solid and liquid phases. According to the results, using perforated fins intensifies the buoyancy force by increasing fluid displacement inside the enclosure. As a result, using 24 perforations on each fin with a D/δ = 2 improves the liquid fraction up to 9.7%. Moreover, the change of geometry reduces the critical area at the bottom of the system and improves the liquid fraction up to 5.4% inside the trapezoidal enclosure. By applying two ideas of using perforated fins and changing the geometry simultaneously, the mean Nusselt numbers for rectangular, trapezoidal, and parallelogram enclosures are significantly enhanced by 95, 114, and 133%, respectively. In these cases, the improvement in the heat transfer rate has led to a decrease in the melting time of the materials by 44.5, 47.5, and 51.5 min, respectively. These operational suggestions also enhance the critical performance parameters of the system, namely the stored energy and the mean charging power from 946 kJ/m and 124 W/m (in the base case) to 963 kJ/m and 211 W/m (70%) (in the rectangular enclosure with perforated fins).

Methyl ammonium iodide via novel PECVD process for the growth of 2-step vacuum based perovskite (MAPbI3) thin films

MAPbI3 thin films were grown via 2-step vacuum based processes by depositing methyl ammonium iodide (MAI) layer as first step using plasma enhanced chemical vapour deposition (PECVD) technique and then depositing lead iodide (PbI2) layer over it as second step using RF-sputtering technique. To the best of our knowledge MAI layer was deposited for the first time by PECVD technique. MAI solution for PECVD process and PbI2 target for sputtering process were made to deposit these two layers under optimized plasma conditions for the growth of MAPbI3 thin films. Characterization techniques like UV-Vis-NIR spectroscopy and Photoluminescence spectroscopy were performed to study the optical properties. Powder-XRD (PXRD) and glancing incidence XRD (GIXRD) were performed to study structural properties. SEM and cross-SEM were performed for morphological study to view top-view and cross-sectional view of the deposited MAPbI3 perovskite thin film. Perovskite thin films deposited on silicon wafer have been used as perovskite/silicon heterojunction photodiode exhibiting critical performance parameters such as rectifying ratio of 1.58 × 104 at 1.0 V, photo-sensitivity value 7.46 × 102 at light intensity 100 mw/cm2 without biasing.

Heterogeneous Catalyst as a Functional Substrate Governing the Shape of Electrochemical Precipitates in Oxygen-Fueled Rechargeable Batteries.

Lithium-oxygen batteries have the potential to become the most eminent solution for future energy storage with their theoretical energy density exceeding all existing batteries. However, the insulating and insoluble discharge product (lithium peroxide; Li2O2) impairs practical application. Conventional catalyst designs based on the electronic structure and interfacial charge transfer descriptors have not been able to overcome these limitations due to Li2O2. Herein, we revisit the role of heterogeneous catalysts as substrates to regulate Li2O2 growth and the formation of solid/solid reaction interfaces. We demonstrate that controlled solid/solid interfacial structure design is a critical performance parameter beyond the inherent electronic structure. In particular, the Cu2O substrate in this study induces a homogeneous deposition of Pd atoms, which leads to well-controlled growth of Li2O2 resolving mass and charge transport limits (i.e., the bottleneck of oxygen reduction/evolution reactions), thus improving reversibility, capacity, and durability of the cells by dissipating electrochemical and mechanical stress. We thus verified the essential role of solid/solid interfaces to regulate the nucleation and growth process of Li2O2 in lithium-oxygen batteries.

Association of Gene Variants with Seasonal Variation in Muscle Strength and Aerobic Capacity in Elite Skiers.

Background: The training of elite skiers follows a systematic seasonal periodization with a preparation period, when anaerobic muscle strength, aerobic capacity, and cardio-metabolic recovery are specifically conditioned to provide extra capacity for developing ski-specific physical fitness in the subsequent competition period. We hypothesized that periodization-induced alterations in muscle and metabolic performance demonstrate important variability, which in part is explained by gene-associated factors in association with sex and age. Methods: A total of 34 elite skiers (20.4 ± 3.1 years, 19 women, 15 men) underwent exhaustive cardiopulmonary exercise and isokinetic strength testing before and after the preparation and subsequent competition periods of the World Cup skiing seasons 2015-2018. Biometric data were recorded, and frequent polymorphisms in five fitness genes, ACE-I/D (rs1799752), TNC (rs2104772), ACTN3 (rs1815739), and PTK2 (rs7460, rs7843014), were determined with specific PCR reactions on collected DNA. Relative percentage changes of cardio-pulmonary and skeletal muscle metabolism and performance over the two seasonal periods were calculated for 160 data points and subjected to analysis of variance (ANOVA) to identify hypothesized and novel associations between performance alterations and the five respective genotypes and determine the influence of age × sex. A threshold of 0.1 for the effect size (h2) was deemed appropriate to identify relevant associations and motivate a post hoc test to localize effects. Results: The preparation and competition periods produced antidromic functional changes, the extent of which varied with increasing importance for anaerobic strength, aerobic performance, cardio-metabolic efficiency, and cardio-metabolic/muscle recovery. Only peak RER (-14%), but not anaerobic strength and peak aerobic performance, and parameters characterizing cardio-metabolic efficiency, differed between the first and last studied skiing seasons because improvements over the preparation period were mostly lost over the competition period. A number of functional parameters demonstrated associations of variability in periodic changes with a given genotype, and this was considerably influenced by athlete "age", but not "sex". This concerned age-dependent associations between periodic changes in muscle-related parameters, such as anaerobic strength for low and high angular velocities of extension and flexion and blood lactate concentration, with rs1799752 and rs2104772, whose gene products relate to sarcopenia. By contrast, the variance in period-dependent changes in body mass and peak VO2 with rs1799752 and rs2104772, respectively, was independent of age. Likely, the variance in periodic changes in the reliance of aerobic performance on lactate, oxygen uptake, and heart rate was associated with rs1815739 independent of age. These associations manifested at the post hoc level in genotype-associated differences in critical performance parameters. ACTN3 T-allele carriers demonstrated, compared to non-carriers, largely different periodic changes in the muscle-associated parameters of aerobic metabolism during exhaustive exercise, including blood lactate and respiration exchange ratio. The homozygous T-allele carriers of rs2104772 demonstrated the largest changes in extension strength at low angular velocity during the preparation period. Conclusions: Physiological characteristics of performance in skiing athletes undergo training period-dependent seasonal alterations the extent of which is largest for muscle metabolism-related parameters. Genotype associations for the variability in changes of aerobic metabolism-associated power output during exhaustive exercise and anaerobic peak power over the preparation and competition period motivate personalized training regimes. This may help to predict and maximize the benefit of physical conditioning of elite skiers based on chronological characteristics and the polymorphisms of the ACTN3, ACE, and TNC genes investigated here.

Developing Enzyme Immobilization with Fibrous Membranes: Longevity and Characterization Considerations.

Fibrous membranes offer broad opportunities to deploy immobilized enzymes in new reactor and application designs, including multiphase continuous flow-through reactions. Enzyme immobilization is a technology strategy that simplifies the separation of otherwise soluble catalytic proteins from liquid reaction media and imparts stabilization and performance enhancement. Flexible immobilization matrices made from fibers have versatile physical attributes, such as high surface area, light weight, and controllable porosity, which give them membrane-like characteristics, while simultaneously providing good mechanical properties for creating functional filters, sensors, scaffolds, and other interface-active biocatalytic materials. This review examines immobilization strategies for enzymes on fibrous membrane-like polymeric supports involving all three fundamental mechanisms of post-immobilization, incorporation, and coating. Post-immobilization offers an infinite selection of matrix materials, but may encounter loading and durability issues, while incorporation offers longevity but has more limited material options and may present mass transfer obstacles. Coating techniques on fibrous materials at different geometric scales are a growing trend in making membranes that integrate biocatalytic functionality with versatile physical supports. Biocatalytic performance parameters and characterization techniques for immobilized enzymes are described, including several emerging techniques of special relevance for fibrous immobilized enzymes. Diverse application examples from the literature, focusing on fibrous matrices, are summarized, and biocatalyst longevity is emphasized as a critical performance parameter that needs increased attention to advance concepts from lab scale to broader utilization. This consolidation of fabrication, performance measurement, and characterization techniques, with guiding examples highlighted, is intended to inspire future innovations in enzyme immobilization with fibrous membranes and expand their uses in novel reactors and processes.

Electro-chemo-mechanical finite-element model of single-crystal and polycrystalline NMC cathode particles embedded in an argyrodite solid electrolyte

All-solid-state batteries (ASSB) are emerging as a high-performance alternative to Li-ion batteries. However, some technical challenges need to be overcome before commercialization. Understanding and improving the chemo-mechanical behavior is considered one of the fundamental challenges in the development of ASSB. This work develops a continuum-level, two-dimensional finite-element model that predicts electro-chemo-mechanical responses of a cathode particle in contact with, and surrounded by, solid electrolyte. The model incorporates physics such as structural anisotropy, intergranular particle fracture, cathode embrittlement upon lithiation and cycling, and intragranular separation at cathode-electrolyte interfaces. The model results compare electrochemical performance between single-crystal and randomly oriented polycrystalline cathode particles. Additionally, performance is predicted at several operating pressures. The manuscript considers LiXNi0.8Mn0.1Co0.1O2 (NMC811) electrode particles surrounded by Li6PS5Cl (LPSC) solid-state electrolyte. The model aims to inform the design of microstructures and operating conditions that limit or prevent mechanical damage during electrochemical cycling of all-solid-state batteries. The results indicate the superior performance of single-crystal NMC811 particles with smaller sizes and higher applied pressure. The highest degradation is predicted in the first cycle. Particle size is identified as a critical parameter for composite electrode performance.

Structural behavior of steel dowel-reinforced cross-laminated bamboo and timber beams

Cross-laminated bamboo and timber (CLBT) products exemplify the efficient utilization of bamboo and timber resources, demonstrating excellent potential in sustainable structural engineering. The significant difference in mechanical properties between high-density engineered bamboo and low-density timber laminations leads to premature in-plane delamination failure and loss of ductility and energy absorption for CLBT members subjected to out-of-plane loading. This study demonstrated that vertically-driven steel dowels significantly enhanced the layer combination efficiency and addressed the above problems of CLBT. A comparison of measured critical mechanical performance parameters was presented, systematically characterizing the structural behavior of CLBT beams with steel dowels. Steel dowels in CLBT were more effective than those in cross-laminated timber at resisting high in-plane shear stress and exhibiting the progressive failure phenomenon. Although steel dowels slightly reduced the bending stiffness in some specimens, they increased the ductility and energy absorption performance, particularly in CLBT. This study provides a potential solution for improving the structural behavior of CLBT members subjected to out-of-plane loads under high in-plane shear stress conditions.

A comprehensive investigation of a water and energy-based waste integrated system: Techno-eco-environmental-sustainability aspects

In this work, a novel biomass gasifier combined energy system was offered for potable water, heating load, and power generation. The system included a gasifier, an S–CO2 cycle, a combustor, a domestic water heater, and thermal desalination unit. The plant was evaluated from various aspects, i.e., energetic, energetic, exergo-economic, sustainability, and environmental. To this aim, modeling of the suggested system was conducted by EES software; then, a parametric inquiry was carried out to detect the critical performance parameters, considering an environmental impact indicator. The results showed that the freshwater rate, Levelized CO2 emissions, total cost, and sustainability index of 21.19 kg s−1, 0.563 t.MWh−1, 13.13 $.GJ−1, and 1.53 were acquired, each. Moreover, the combustion chamber is a major fount in the irreversibility of the system. Besides, the energetic and exergetic efficiencies were computed at 89.51% and 40.87%. Overall, the offered water and energy-based waste system showed great functionality in terms of thermodynamic, economic, sustainability, and environmental standpoints by enhancing the gasifier temperature.

Povećanje efikasnosti guseničnog vozila optimizacijom prenosnih odnosa i strategije promene stepena prenosa

Introduction/purpose: Tracked vehicles play a vital role across various domains, from military operations to construction and agriculture. This study focuses on improving the efficiency of tracked vehicles by optimizing both gear ratios and gear-shifting strategies while preserving other performance aspects. Methods: The optimization process involves a genetic algorithm for determining optimal gear ratios, considering performance constraints. Furthermore, the paper introduces a gear-shifting optimization algorithm aimed at enhancing fuel economy to the maximum, while allowing for a valid comparison between two sets of gear ratios. Results: Optimizing gear ratios leads to substantial reductions in fuel consumption, as the engine operates within more efficient regions. Additionally, the optimized gear-shifting strategy further enhances efficiency, resulting in a fuel consumption reduction exceeding 12%, when combined with the optimized gear ratios. Conclusions: This paper offers a direct and robust approach for optimizing powertrain gear ratios and gear-shifting strategies in tracked vehicles. The results demonstrate significant improvements in fuel efficiency without compromising other critical vehicle performance parameters.

Modeling and Simulation of Circuit-Level Nonidealities for an Analog Computing Design Approach With Application to EEG Feature Extraction

This article presents a design approach for the modeling and simulation of ultralow power (ULP) analog computing machine learning (ML) circuits for seizure detection using electroencephalography (EEG) signals in wearable health monitoring applications. In this article, we describe a new analog system modeling and simulation technique to associate power consumption, noise, linearity, and other critical performance parameters of analog circuits with the classification accuracy of a given ML network, which allows to realize a power and performance optimized analog ML hardware implementation based on diverse application-specific needs. We carried out circuit simulations to obtain nonidealities, which are then mathematically modeled for an accurate mapping. We have modeled noise, nonlinearity, resolution, and process variations such that the model can accurately obtain the classification accuracy of the analog computing-based seizure detection system. Noise has been modeled as an input-referred white noise that can be directly added at the input. Device process and temperature variations were modeled as random fluctuations in circuit parameters, such as gain and cut-off frequency. Nonlinearity was mathematically modeled as a power series. The combined system level model was then simulated for classification accuracy assessments. The design approach helps to optimize power and area during the development of tailored analog circuits for ML networks with the ability to potentially trade power and performance goals while still ensuring the required classification accuracy. The simulation technique also enables to determine target specifications for each circuit block in the analog computing hardware. This is achieved by developing the ML hardware model, and investigating the effect of circuit nonidealities on classification accuracy. Simulation of an analog computing EEG seizure detection block shows a classification accuracy of 91%. The proposed modeling approach will significantly reduce design time and complexity of large analog computing systems. Two feature extraction approaches are also compared for an analog computing architecture.

Exploring electromechanical utility of GaAs interdigitated transducers; using finite-element-method-based parametric analysis and experimental comparison

Analysis of interdigitated transducers often relies on phenomenological models to approximate device electrical performance. While these approaches prove essential for signal processing applications, phenomenological models provide limited information on the device’s mechanical response and physical characteristics of the generated acoustic field. Finite element method modeling, in comparison, offers a robust platform to study the effects of the full device geometry on critical performance parameters of interdigitated transducer devices. In this study, we fabricate a surface acoustic wave resonator on semi-insulating GaAs (100), which consists of an interdigitated transducer and acoustic mirror assembly. The device is subsequently modeled using fem software. A vector network analyzer is used to measure the experimental device scattering response, which compares well with the simulated results. The wave characteristics of the experimental device are measured by contact-mode atomic force microscopy, which validates the simulation’s mechanical response predictions. We further show that a computational parametric analysis can be used to optimize device designs for series resonance frequency, effective coupling coefficient, quality factor, and maximum acoustic surface displacement.

Nanometer-Thick Oxide Semiconductor Transistor with Ultra-High Drain Current.

High drive current is a critical performance parameter in semiconductor devices for high-speed, low-power logic applications or high-efficiency, high-power, high-speed radio frequency (RF) analogue applications. In this work, we demonstrate an In2O3 transistor grown by atomic layer deposition (ALD) at back-end-of-line (BEOL) compatible temperatures with a record high drain current in planar FET, exceeding 10 A/mm, the performance of which is 2-3 times better than all known transistors with semiconductor channels. A high transconductance reaches 4 S/mm, recorded among all transistors with a planar structure. Planar FETs working ballistically or quasi-ballistically are exploited as one of the simplest platforms to investigate the intrinsic transport properties. It is found experimentally and theoretically that a high carrier density and high electron velocity both contribute to this high on-state performance in ALD In2O3 transistors, which is made possible by the high-quality oxide/oxide interface, the metal-like charge-neutrality-level (CNL) alignment, and the high band velocities induced by the low density-of-state (DOS). Experimental Hall, I-V, and split C-V measurements at room temperature confirm a high carrier density of up to 6-7 × 1013 /cm2 and a high velocity of about 107 cm/s, well-supported by density functional theory (DFT) calculations. The simultaneous demonstration of such high carrier concentration and average band velocity is enabled by the exploitation of the ultrafast pulse scheme and heat dissipation engineering.