Multilayer Design Research Articles

Deeper mechanistic insights into epitaxial nickelate electrocatalysts for the oxygen evolution reaction.

Mass production of green hydrogen via water electrolysis requires advancements in the performance of electrocatalysts, especially for the oxygen evolution reaction. In this feature article, we highlight how epitaxial nickelates act as model systems to identify atomic-level composition-structure-property-activity relationships, capture dynamic changes under operating conditions, and reveal reaction and failure mechanisms. These insights guide advanced electrocatalyst design with tailored functionality and superior performance. We conclude with an outlook for future developments via operando characterization and multilayer electrocatalyst design.

Fast PCB Stack-Up Optimization Using Integer Programming

This paper presents a flexible and efficient methodology to optimize stack-up for multi-layer printed circuit boards (PCBs) with enormous search space and various design constraints. PCB stack-up optimization is crucial in high-speed system design to achieve the desired electrical performance while reducing system costs. The stack-up optimization process is labor-intensive and time-consuming for a large number of layers. Moreover, after the optimization process, the electrical performance of a real design, such as the impedance and loss, may deviate from the target design due to manufacturing variations. Estimating the worst cases due to the manufacturing variations, referred to as “corner cases” in this paper, is essential for a confident PCB design but challenging since the number of related parameters is large. In this paper, PCB stack-up optimization and corner-case searching are addressed and greatly accelerated using the integer programming technique. All constraints are converted to mathematical equalities and inequalities that can be solved rapidly by an integer programming solver to obtain feasible stack-up solutions. After the cross-sections of the transmission lines are optimized based on the stack-up design to achieve a target electrical performance, the upper and lower bound of impedance and loss are acquired using integer programming when the design parameters vary in a particular range. The proposed method is verified using multi-layer PCB designs with practical constraints and demonstrates its effectiveness and high efficiency.

The dependence of timing jitter of superconducting nanowire single-photon detectors on the multi-layer sample design and slew rate.

We investigated the timing jitter of superconducting nanowire single-photon detectors (SNSPDs) and found a strong dependence on the detector response. By varying the multi-layer structure, we observed changes in pulse shape which are attributed to capacitive behaviour affecting the pulse heights, rise times and consequently timing jitter. Moreover, we developed a technique to predict the timing jitter of a single device within certain limits by capturing only a single detector pulse, eliminating the need for detailed jitter measurement using a pulsed laser when a rough estimate of the timing jitter is sufficient.

Capability and limits of the technology of complex optical interference filters

Over the last 15 years, there have been tremendous progress in the technology of optical interference filters. Nowadays, it is more and more common to fabricate optical interference filters that can combine several tens to several hundreds of layers in order to produce more and more complex optical functions. These progresses are the result of improved multilayer structures modeling and design procedures, the introduction of Virtual Deposition Process, and the development of performant physical vapor deposition machines associated with in-situ optical monitoring. In this paper, we will present actual state-of-the-art of these technologies and some typical examples of filters. We will then present some of the actual challenges and outlook in order to produce more and more performant optical components.

Spectrum-Aware Compact Reconfigurable UHF Antenna for Interweave Cognitive Radio

This paper presents a compact ultra-high frequency (UHF) folded antenna design that relies on a single radio frequency micro-electro-mechanical switch (RF-MEMS) to reconfigure its frequency of operation between 575 MHz and 760 MHz. The reconfigurable multi-layered antenna design has a volumetric folded topology with total dimensions of 40×40mm2; equivalent to 0.11λx0.11λ at 575 MHz. The antenna is fabricated and tested where the measurements agree well with the simulation results. The antenna exhibits a radiation efficiency of 40% at 575 MHz and 62% at 760 MHz. Furthermore, the proposed antenna is tested in a cognitive radio environment to validate its ability to adapt to cognitive input and tune its performance across white space within the UHF band. This is achieved by relying on a trained classifier model that is embedded within a microcontroller to autonomously control the state of the integrated switch based on which channel is idle.

Innovative selective solar absorber for high vacuum flat panel

Selective Solar Absorbers (SSAs) are the critical element of high-vacuum flat plate collectors, as these are subject to elevated operating temperatures and thus experience high radiation losses. Here we design and optimize an SSA based on a multilayer design made of HfCx, Si3N4, and SiO2 layers. The structure of the proposed SSA has been optimized to maximize the solar-to-thermal energy conversion efficiency in high vacuum solar thermal panels working at 200 °C, reaching thermal emissivity values much lower than absorbers currently available on the market (<0.02 Vs >0.07) and obtaining unprecedented performances.

Selective Emitter for Solar Thermophotovoltaic Applications

Selective Emitters (SEs) are the main components of solar thermophotovoltaic (STPV) systems; they act as intermediate thermal radiation emitters to shape the incident solar spectrum to match the wavelengths useful for the PV cell. In this work, we present the design, optimisation, fabrication, and characterisation of an SE based on a multilayer design made of SiNx, SiO2, and TiO2 layers. The SE is optimised to work with PV cells based on III-V semiconductors, such as GaSb, InGaAs, and InGaAsS, the bests suitable for SPTV applications. The fabricated SE shows an emitter efficiency (ηSE) of 50% if matched with a PV cell with an energy bandgap of 0.63 eV.

Simultaneous Realization of Good Piezoelectric and Strain Temperature Stability via the Synergic Contribution from Multilayer Design and Rare Earth Doping

AbstractNiobate‐based lead‐free piezoceramics have attracted wide attention due to their excellent piezoelectric properties. Although the temperature sensitivity of piezoelectricity or strain in one sample has been solved to a certain extent, how to simultaneously improve the temperature stability of both in one sample is still an issue. Herein, by constructing multilayer composite ceramics and doping Ho element, both improved piezoelectric and strain temperature stability (the variations are below 3% under 30–100 °C) are achieved, showing great property advantage compared with previous reports. Different from the compositionally graded composite ceramic design, the Ho doping can not only increase orthorhombic‐tetragonal phase transition temperature (TO‐T) and then create the condition for the formation of successive phase transition, but also stabilize the oriented domain state. Therefore, the excellent temperature stability of both piezoelectricity and strain can be attributed to the multistep phase transition induced by the multilayer design, the fine regulation of TO‐T interval by the optimization of lamination combination, and the stabilized polarization induced by Ho doping. The new strategy for solving both piezoelectric and strain temperature sensitivity can further promote the commercial application of potassium sodium niobate‐based lead‐free piezoelectric ceramics.

Transparent planar solar absorber for winter thermal management

Indoor heating during winters accounts for a significant portion of energy consumed by buildings in regions of cold climate. Development of transparent coatings for windows that efficiently harvest solar energy can play a major role in reducing energy consumption and fuel costs incurred for winter heating. In recent years, there has been a great research effort towards designing transparent solar absorber coatings using nanophotonic structures. The potential of coatings based on planar multilayer structures, however, has received very little attention. In this work we investigate the performance of planar multilayer thin films using low-cost materials for design of transparent solar absorber window coatings. Our study led to the proposal of two planar multilayer designs. Simulation results predict that an increase in surface temperature by 27 K and 25 K, while maintaining mean visible transmittance of over 50% is possible using these designs. These results illustrate the great promise planar multilayer structures hold for winter thermal management of buildings.

Automated design of 3D DNA origami with non-rasterized 2D curvature

Improving the precision and function of encapsulating three-dimensional (3D) DNA nanostructures via curved geometries could have transformative impacts on areas such as molecular transport, drug delivery, and nanofabrication. However, the addition of non-rasterized curvature escalates design complexity without algorithmic regularity, and these challenges have limited the ad hoc development and usage of previously unknown shapes. In this work, we develop and automate the application of a set of previously unknown design principles that now includes a multilayer design for closed and curved DNA nanostructures to resolve past obstacles in shape selection, yield, mechanical rigidity, and accessibility. We design, analyze, and experimentally demonstrate a set of diverse 3D curved nanoarchitectures, showing planar asymmetry and examining partial multilayer designs. Our automated design tool implements a combined algorithmic and numerical approximation strategy for scaffold routing and crossover placement, which may enable wider applications of general DNA nanostructure design for nonregular or oblique shapes.

ARCHITECTURAL DESIGN WITH GENERATIVE ALGORITHM AND VIDEO PROJECTION MAPPING

The innovative and creative approach that is produced for architectural design problems involves quite complex stages. In architectural design, the designer's approach and numerical data make the design process a multi-layered structure. The integration of parametric modeling programs and generative algorithms makes it easy to carry out multi-layered design processes. Generative systems defined through generative algorithms enable conceptual approaches, various geometrical constructs, and different forms to be created in digital environments in solving design problems. The creation of the generative algorithm of the design eliminates the restrictive role of modeling software in the architectural design. The designer gets the opportunity to create every parameter and design criteria specific to his approach. 
 In this study, our aim is to develop a generative algorithm in a computer environment by using the principles of fractal geometry function. The generative system creates by overlaying the developed generative algorithm with the environmental factor parameters. In this system proposal, the goal is to produce various facade design proposals by coding the algorithm fractal functions and to make use of the visualization of various potentials of the generative algorithm in parametric facade proposals. Video projection mapping method is chosen to discuss the functionality of the parameters in the proposed generative system of the developed generative algorithm. Computation of the transformation relating consecutive image frames is an essential operation in video mapping. In this context, the design created with the generative system is reflected on a real scale medium , specifically a column in this study, and various image frames letting new design proposals produced by the algorithm were evaluated. In concluding rmarks, the advantages of architectural designs modeled by coding with the generative algorithm compared to the algorithms obtained directly with the software are discussed.

Performance Assessment of Using Multilayer Inductors in Induction Installations for Heating Aluminum Billets

A mathematical model for numerically analyzing the electrical characteristics of a multilayer inductor – billet system is developed. The model is based on the finite element method and implemented in the ELCUT software package. The system electrical characteristics depending on different billet sizes, inductor geometry, gap sizes, and system design area sizes are obtained. The influence of end effects and magnetic core on the multilayer inductor – billet system is studied. Based on the simulation results, recommendations on improving the energy efficiency of induction installations for heating aluminum billets owing to smaller losses achieved by modifying the multilayer inductor designs have been developed.

Evolutionary design of two-dimensional material Fabry–Perot structures for enhanced second harmonic generation

Abstract The integration of two-dimensional (2D) materials with resonant photonic structures is seen as a promising direction for enhancing its nonlinear optical response. The design of such heterogeneous resonant structures has often relied on multi-parameter sweeps to determine the optimized dimensions of resonant optical structure that results in good resonance characteristics, often in the absence of the 2D material. Such an approach is computationally intensive and may not necessarily result in efficient generation or collection of nonlinear signals from the designed structure. Here, we report hybrid-genetic optimization (HGA) based design and experimental demonstration of second harmonic generation (SHG) enhancement from Fabry–Perot structures of single and double multilayer gallium selenide (GaSe) flakes with bottom silicon dioxide, and index matched polymethyl methacrylate spacer/encapsulation layers. HGA technique utilized here speeds up the multilayer cavity design by 8.8 and 89-times for the single and double GaSe structures when compared to the full parameter-sweep, with measured SHG enhancement of 128- and 400-times, respectively, when compared to a reference sample composed of GaSe layer of optimized thickness on 300 nm silicon dioxide layer. SHG conversion efficiencies obtained from the HGA structures are 1–2 orders of magnitude higher than previous reports on 2D material integrated resonant metasurfaces or Bragg cavities.

Influence of Alternating Multi-Layered Design on Damping Characteristics of Butyl Rubber Composites and a New Idea for Achieving Wide Temperature Range and High Damping Performance.

This paper investigates the influence of an alternating multi-layered design on the material loss factor and effective temperature range of free/constrained-damping butyl rubber, and then proposes a new method of designing materials with high damping properties and a wide temperature range. First, the wide-temperature rubber IIR-0, the low-temperature rubber IIR-1, the medium-temperature rubber IIR-2, and the high-temperature rubber IIR-3 are prepared and characterized. Second, the influences of an alternating multi-layered design on the damping peak values and temperature range of free damping and micro-constrained damping of the rubber types are investigated. Finally, different methods for broadening the damping temperature range and improving the damping loss factor are discussed. The results show that the loss factor of the alternating multi-layered, constrained damping structure is increased to 0.488, while that of the free-damping structure is increased to 0.845. Their damping-temperature ranges are increased to 89.4 °C and 93.2 °C, respectively. A wide temperature range and high damping performance can be achieved by the alternating multi-layered design of rubber/plastic micro-constrained damping composites.

Analytical and 3D Numerical Study of Multilayer Shielding Effectiveness for Board Level Shielding Optimization

The strong development of solid-state power sources offers numerous benefits (such as higher operating frequencies and reduced switching times and power losses), but contributes inherently to the extended range of electromagnetic interferences (EMI). As these systems are associated with a set of embedded monitoring devices using low amplitude signals, it becomes necessary to consider new critical cases of electromagnetic (EM) immunity correlated to such environments. The most common solution against aggressive radiated EMI is the metallic enclosure, which brings a strong shielding effectiveness (SE), but is it always the best compromise? Our study in this paper is focused on the SE of multilayer designs and is therefore intended to optimize the enclosures’ compactness for board level shielding (BLS) on printed circuit boards (PCB). First, results are presented, based on metallic multilayer shielding theory and parametric numerical studies in the intentional electromagnetic interferences (IEMI) frequency range, from 0.2 to 5 GHz. Then, a complete 3D EM co-simulation model using the microwave and design modules of CST Studio Suite (which includes the subject, the EMI radiating source, and the multilayer shielding) is proposed, with emphasis on the pertinent choices regarding layers width and their arrangement for compact EM shielding and immunity optimization.

Utilizing Multilayer Design of Organic-Inorganic Hybrids to Enhance Wearable Strain Sensor in Humid Environment

Utilizing Multilayer Design of Organic-Inorganic Hybrids to Enhance Wearable Strain Sensor in Humid Environment

Enhanced high dielectric characteristics tri‐layered structural ceramics for 5G/6G communications

AbstractTri‐layered structural Zn0.997Cu0.003ZrNb2O8–TiO2+ZnO/TiO2+CuO/TiO2–Zn0.997Cu0.003ZrNb2O8 ceramics with different mass fractions of TiO2+ZnO/TiO2+CuO/TiO2 were successfully prepared. The advantages of the multilayered design were completely demonstrated, and the microwave dielectric characteristics were modified by the components of each dielectric layer. In comparison to the random distribution‐type, Zn0.997Cu0.003ZrNb2O8@TiO2+ZnO, this tri‐layered construction could increase the Q f value by approximately 100%. Meanwhile, based on the electronic compensation mechanisms, the Q f value of the tri‐layered structural ceramics with TiO2‐doped interlayer can be increased by nearly 20% compared with that of the pure TiO2 interlayer. The Zn0.997Cu0.003ZrNb2O8–TiO2+ZnO–Zn0.997Cu0.003ZrNb2O8 tri‐layered ceramic exhibited excellent dielectric characteristics ( = 33.75, Q × f = 59 000 GHz, and = +2.27 ppm/°C) with 0.05 wt% TiO2+ZnO sintered at 1240°C for 6 h, and the integrated optimization of microwave dielectric characteristics was achieved. This article provides a strategy for the synthesis of high‐performance microwave dielectric components for application in 5G/6G wireless communication technologies.

Flexible and Transparent Ionic Liquids/Poly(vinylidene fluoride) Composition‐Gradient Piezo‐Active Composites for Highly Sensitive Pressure Sensor

AbstractNowadays, the advent of pressure sensors for intelligence terminal devices and skin‐inspired electronics has trigged rapid development of flexible, sensitive, and transparent sensing materials. Piezo‐active poly(vinylidene fluoride) (PVDF) is emerging as a promising candidate for sensing components due to the flexible and transparent features. However, the inherent weak piezo‐activity and consequently low sensitivity of PVDF remains a challenge for its sensing applications. Herein, ionic liquids ([EMIM]Cl) additive combined with a composition‐gradient multilayered architecture design are employed to hardness the piezo‐response of PVDF. The resultant composites present ultra‐high piezoelectric coefficient d33 of 39 pC N−1, which is 2.78 times that of PVDF. Meanwhile, the transparent ILs dopant enables the composites with superior transparency (87%). With notable advantages of high transparency and piezoelectricity, the ILs/PVDF composites exhibit high sensitivity of 0.0423 V N−1, ultra‐fast recovery time of 0.2 ms and stable operation capability when coupled with metal electrodes, confirming their applicability for reliable pressure sensor.

Direct-current, long-lasting and highly efficient electret energy harvesting from ultra-low-frequency motions using toothed clutch mechanism

Generally, most wearable energy harvesters generate only a small amount of electrical energy from the low-frequency motions of human body and immediately stop working when the activity ends, resulting in low energy extraction efficiency. Here, we propose an electret rotatory energy harvester (e-REH) with a mechanical tooth-clutch transmission system, converting the ultra-low-frequency irregular human motion (< 0.1 Hz) into a high-speed and long-lasting rotation for boosted energy conversion efficiency. The tooth-clutch transmission system is designed with a compact integration of a linear-to-rotation unit, a tooth-clutch transmission unit and an energy storage unit to generate continuous, stable and highly efficient electrical output. Triggered by impulse excitation of gentle hand tapping, the flywheel can continuously rotate for about 45 s inertially, and the maximum speed of the flywheel can reach about 1500 rpm, indicating the frequency is increased up to 4500 times from 0.022 Hz to 100 Hz. In addition, by introducing the multi-layer phase-shift electrode design, a constant direct-current output with a crest factor down to 1.09 is obtained by the phase coupling effect, avoiding the complicated signal processing circuit. Experimental results show the fabricated e-REH can produce an overall coupling current of 22.1 μA and average output power of 3.95 mW. Thanks to the lightweight, compact and high-efficient transmission design, the e-REH is further integrated into a shoe for wearable energy harvesting and self-powered underground environmental monitoring applications. The research is of considerable significance to the practical applications of e-REH in powering sensors and building self-powered wearable sensor networks.

A practical procedure for vehicle sound package design using statistical energy analysis

Vehicle sound package has a substantial role in attenuation of vehicle noise for the purpose of improving interior comfort and reducing environmental noise pollution. In this paper, two approaches of absorptive design and multi-layer design are investigated to improve the performance of a sound package in automotive applications. For this purpose, the sound package of the engine compartment including hoodliner and dash insulator is studied. Furthermore, this paper proposes an experimentally validated prediction model through Statistical Energy Analysis (SEA) to evaluate the sound insulation of a vehicle body sound package. For this purpose, the research includes characterization techniques of sound package materials to determine intrinsic parameters of different layers required to develop a reliable SEA model. The inverse method and time-temperature superposition principle (TTSP) are utilized to characterize porous materials and heavy layer properties, respectively. The comparison of results that are experimentally obtained by acoustic cabin shows a fairly well agreement with the proposed SEA modeling procedure for the desired frequency range. By observing the results of the simulation for the hoodliner and dash insulator, it was revealed that the absorptive design combines the benefits of high sound absorption capability, wide absorption frequency band, and lightweight. Indeed, with an appropriate combination of layers, the multi-layer design can simultaneously provide a mixture of absorptive design attributes and sound insulation capabilities. The transmission loss obtained from the proposed design of the dash insulator revealed an increase by 42% without any reduction in the amount of sound absorption. Also, the sound absorption of the proposed hoodliner is enhanced more than twice in reference to the base design.