Wire arc additive manufacturing (WAAM) is emerging as a scalable route for fabricating large-scale, coarse, strut-based metallic lattice structures that are difficult to produce within a typical laser-based powder bed fusion build-volume and powder-removal constraints. Given the rapid growth of this field, a systematic review is needed to consolidate current progresses and clarify barriers to the engineering adoption. This review examines WAAM lattice structures across slicing and toolpath planning, fabrication strategy, lattice design, fabrication quality analysis, mechanical performance, finite element modelling, applications, and standardisation. Existing studies have demonstrated mainly strut-based lattices in steels, aluminium alloys, titanium alloys, and copper-based alloys, with mechanical performance evaluated through tensile, compression, bending, and hardness testing at both strut and lattice scales. Finite element models can capture case-specific stress and thermal trends, but their predictive accuracy remains limited by nominal digitally-designedgeometry, simplified constitutive behaviour, insufficient node morphology, and weak thermal-history coupling. Demonstrated and prospective applications include civil construction, aerospace, marine engineering, and energy absorption. However, broader implementation is still constrained by immature lattice-aware slicing, gravity-induced strut instability, node control, restricted topology diversity, and inconsistent terminology. Mechanical testing should draw on existing additive manufacturing, cellular-metal, tensile and bending standards, but these frameworks must be adapted before they can serve as qualification protocols for WAAM lattices.
Hydrogel bioelectronic interfaces have emerged as a pivotal platform for next-generation wearable and implantable electrical/electrochemical bioelectronic systems. However, the performance of bioelectronic devices is fundamentally governed not by the device itself, but by the functionality of the hydrogel–tissue interface. Key interfacial requirements, including low impedance, conformal contact, robust yet controllable adhesion, and minimal interfacial noise, are intrinsically coupled and often exhibit trade-offs, rendering empirical optimization inefficient and incomplete. We first delineate the fundamental interfacial requirements across representative applications such as electrophysiological monitoring, wound healing, neuromodulation, and electrochemical sensing. We then systematically summarize material and structural strategies to reduce interfacial impedance, enable conformal contact, enhance adhesion, and suppress mechanical and electrochemical noise. Moving beyond single-property optimization, we highlight co-design principles that address intrinsic trade-offs through mixed matrix hydrogels (MMHs) and gradient/layered hydrogels (GLHs), enabling spatial or compositional decoupling of electrical, mechanical, and adhesive functions. This review establishes a demand-driven design framework for functional hydrogel biointerfaces, systematically summarizing representative strategies for interfacial property engineering. It offers structured guidelines for rational multifunctional hydrogel design and further highlights the emerging potential of AI-assisted approaches in navigating complex structure–property landscapes.
In response to the needs of a rapidly growing private fusion industry, the U.S. Fusion Materials Coordinating Committee (FMCC) and the broader U.S. fusion materials research community undertook an extensive effort to create a comprehensive roadmap for fusion materials development. The result of this effort was the U.S. Fusion Materials Community Roadmap (US-FMCR), which describes the steps needed to advance the technical maturity of leading candidates for plasma-facing materials and structural materials for fusion power plants from laboratory-scale experiments to a point of sufficient technological readiness for industrial adoption and implementation. However, researchers face significant resource constraints as well as very aggressive pilot plant development timelines. Thus, the research strategies detailed in the US-FMCR require further assessment to downselect the specific tasks that must be prioritized within the next two to three years, in order to make the most efficient use of funding, human resources, and experimental facilities. This paper presents an overview of the US-FMCR and its development process. We also present the subset of research objectives that the FMCC identified as the most urgent research priorities for the U.S. fusion materials research community. The state-of-the-art of materials research is also highlighted for each class of materials considered in the US-FMCR. The recommendations presented here integrate an extensive evaluation of the current status of fusion materials research with a broad cross-section of opinion from the wider U.S. fusion community.
Rising power density and device integration have made interfacial heat dissipation a major challenge in thermal management. Thermal interface materials (TIMs) bridge heat sources and sinks, but their practical performance depends on effective thermal resistance rather than thermal conductivity alone. This review focuses on flexible TIMs with low contact thermal resistance and examines how material composition, interfacial interactions, and structural design jointly regulate bulk thermal resistance, bond-line thickness (BLT), and contact thermal resistance (RC). We examine the physical origins of RC and summarize recent strategies based on compliant matrices, interfacial adhesion and wetting, adaptive gap filling, continuous thermal networks, and compressible structures. These studies show that increasing thermal conductivity alone can be ineffective when increased modulus, viscosity, or BLT limits interfacial conformability. We conclude that future TIM development should prioritize the coordinated optimization of thermal pathways, interfacial adaptability, BLT, mechanical reliability, and scalable processing under practical conditions.
Understanding how materials evolve during synthesis, processing, or device operation requires experimental access to structural dynamics across wide ranges of length and time scales, often in bulk samples or even within packaged devices. Time-resolved full-field diffraction X-ray microscopy has recently emerged as a powerful way to meet this need by combining the penetration and structural sensitivity of X-ray diffraction with objective-lens-based magnification, sensitive high-resolution X-ray imaging detectors, and pump-probe and real-time imaging strategies. Advances in full-field X-ray diffraction microscopy, often termed dark-field X-ray microscopy (DFXM), enable simultaneous imaging of extended fields of view while retaining crystallographic selectivity. Time-resolved DFXM promises to enable advances in materials processing and dynamics, electrochemical and photochemical processes, and the design of electronic devices. This Perspective summarizes the key instrumental concepts that define the performance of these methods, including the choice of imaging optics, detector considerations, and the impact of source time structure at synchrotron light sources and X-ray free-electron lasers (XFELs). We discuss the simultaneous use of complementary imaging modes that are increasingly used in practice. The early demonstrations of the potential of time-resolved DFXM include real-time defect and grain-boundary dynamics during metal annealing, stroboscopic imaging of functional devices with high strain sensitivity, and ultrafast pump-probe implementations at XFELs that directly visualize acoustic-wave propagation and energy dissipation in bulk crystals.
Perovskite/silicon tandem solar cells (TSCs) have emerged as a leading platform to surpass the Shockley-Queisser limit of single-junction silicon photovoltaics. By combining the tunable wide-bandgap absorption of perovskites (typically 1.65–1.70 eV) with the excellent surface passivation and high open-circuit voltage of silicon solar cells, certified power conversion efficiencies (PCEs above 34%) have been achieved, with record values exceeding 35.2%. These advances arise from improved bandgap alignment, carrier dynamics, and optical management, enabling efficient current matching and enhanced spectrum utilization. Despite this progress, key challenges persist, including interfacial non-radiative recombination, perovskite phase instability, electrode diffusion at elevated temperatures (>85 °C), and module scalability. In addition, metastability, hysteresis, and spectral mismatch complicate reliable current-voltage (J-V) characterization. Here, we review the stability landscape of perovskite/silicon tandem solar cells, highlighting degradation pathways at both device and module levels. Emphasis is placed on phase segregation, strain effects, and UV/thermal stress, along with energy band engineering (1.58–1.70 eV) and current-matching constraints analyzed using SCAPS 1D simulation. Finally, we outline research priorities toward achieving long-term operational stability (>5000 h) in line with IEC 61215 requirements for commercialization.
Self-powered broadband photodetectors (SPBPDs) have emerged as a promising class of optoelectronic devices that enable detection of light across wide spectral ranges without an external bias voltage, paving the way for energy-efficient photonics systems. Creation of a p-n junction at the semiconductor-semiconductor interface, formation of an asymmetric contact structure at the metal-semiconductor interface, and fabrication of an asymmetric thickness configuration are efficient approaches for developing SPBPDs. In this review, we present a comprehensive analysis and performance comparisons of metal oxide and 2D-materials-based SPBPDs on rigid substrates, using the aforementioned strategies. Additionally, to broaden the applicability of SPBPDs in various aspects, such as heart rate monitoring, omnidirectional self-powered photodetection, optical sensing on plants, wearable electronics, and smart sensors technologies, this review also systematically concludes their performance through the integration with flexible and transparent electronics. Finally, we highlight the prospects of the SPBPDs with flexible and transparent electronics by highlighting the challenges in material fabrication strategies and interfacial charge transfer, advancement in device architecture, and incorporation of machine learning (ML) and artificial intelligence (AI) into the system. We envision that this review perspective will provide a significant pathway for accelerating the deployment of the next-generation optoelectronics systems with flexible and transparent electronics.
As an evolutionary adaptation, a diverse array of helical structures has developed in biological tissues, endowing organisms with exceptional functional properties. These integrated structural-functional biological tissues provide valuable inspiration for the design and fabrication of novel high-performance materials. However, the internal structures of biological tissues are intricate, making it difficult to replicate their forms using traditional manufacturing methods. Additive manufacturing (AM), with its layer-by-layer accumulation approach, enables the fabrication of designed structures through a growth-like process, offering significant advantages in the preparation of structural materials. In this review, we first introduce the coupling relationship between the functions and structures of biological helical tissues. Subsequently, the design and fabrication of bioinspired helical structures enabled by AM are discussed. And the process innovations and structural optimizations based on conventional AM techniques are particularly highlighted to expand the design space for bioinspired helical structures. Following this, the outstanding performance advantages and potential applications of printed bioinspired helical structural samples are elaborated. Finally, we provide an outlook on the future synergistic development between bioinspired helical structural samples and AM processes.
The continuous scaling of complementary metal–oxide–semiconductor (CMOS) technology has reached a stage where fundamental physical limitations increasingly restrict device performance and energy efficiency. Effects such as strong short-channel behavior, direct source–drain tunneling, reduced carrier mobility, and weakened electrostatic control pose significant challenges to further miniaturization in advanced very-large-scale integration (VLSI) systems. These limitations have intensified the search for alternative channel materials capable of maintaining high performance while supporting continued device scaling. Graphene nanofibers (GNFs), a laterally confined form of graphene nanostructures, have emerged as promising candidates for next-generation metal–oxide–semiconductor field-effect transistors (MOSFETs) due to their tunable bandgap, high intrinsic carrier mobility, and excellent thermal conductivity. This article presents recent progress in GNF-based MOS devices, focusing on material synthesis techniques, bandgap engineering strategies, carrier transport mechanisms, innovative device architectures, and prospects for circuit-level integration. Various theoretical and computational approaches-including density functional theory (DFT), non-equilibrium Green’s function (NEGF) methods, drift–diffusion modeling, and compact device modeling using Verilog-A are discussed as essential tools for performance prediction and device optimization. The performance of GNF-based devices is also compared with established technologies such as silicon, germanium, and carbon nanotubes to highlight their potential advantages and associated trade-offs. Finally, key challenges including scalable fabrication, contact resistance, device variability, and long-term reliability are examined, and future research directions for integrating GNFs into practical VLSI systems are outlined.
Topological spin textures and magnetoelectric (ME) couplings are at the forefront of quantum-materials research, offering new routes to control collective electronic and magnetic phenomena. Over the recent past years, significant progress has been made in stabilizing and manipulating skyrmions, Z2 vortices, and related excitations in frustrated and chiral magnets. Lattices crystalizing these topological quasiparticles have also been studied, both in the ferromagnetic and antiferromagnetic cases. It was found in some cases that the skyrmion crystal (SkX) induces an electric polarization, opening the route to control the skyrmion lattices with electric fields. This is a major point of interest for next-generation data storage devices that could operate with lower power consumption compared to metallic systems. On the other hand, lattice distortions have been shown to play a role in the stability of different SkX states, hence epitaxial strain, uniaxial pressure, or chemical substitution could be used to selectively stabilize or suppress SkX phases. Parallel developments in type-II multiferroics have revealed several microscopic mechanisms of ME coupling, of which we discuss the d-p hybridization mechanism and the pantograph effect, driven by lattice distortions, which enable electric-field control of magnetic order and the emergence of magneto-electro-elastic excitations. This perspective highlights key advances from our recent work and the broader community, emphasizing the interplay of competing interactions, structural instabilities, and quantum fluctuations that give rise to these phenomena. We also outline emerging directions, ranging from fractional skyrmion phases to tunable ME responses, that hold promise for energy-efficient devices and neuromorphic architectures. By identifying common principles across seemingly disparate systems, we aim to guide future exploration of quantum materials where topology, magnetism, and lattice degrees of freedom are intimately entangled.
Eco- and bio-friendly polydimethylsiloxane (PDMS) material-based triboelectric nanogenerators (TENGs) have attracted significant attention for applications in energy harvesting, sensing, and self-powered systems. The performance of PDMS-based TENGs is highly dependent on rational material selection and structural engineering within the PDMS matrix. While conventional components such as dielectrics, metals, two-dimensional (2D) materials, and carbon-based fillers have been widely used, there is a growing demand for advanced materials to enhance efficiency and broaden the scope of applications. In this context, a variety of fillers have been explored in PDMS-based TENGs owing to their favorable properties, including biocompatibility, high sensitivity, non-toxicity, and superior electron mobility. These features make them particularly suitable for next-generation energy harvesting technologies. Unlike previous reviews, this work provides an in-depth and systematic overview of PDMS-based TENGs incorporating diverse fillers, with a focus on their impact on triboelectric performance and practical applications. It highlights the influence of these fillers on output efficiency and expands on their use in areas such as energy harvesting, self-powered sensing, human–machine interaction, and wearable devices. The review concludes by outlining current challenges, emphasizing the need for further research, and offering perspectives to guide future developments in this rapidly advancing field.
This study reports a photothermal–radiative cooling–coupled thermoelectric generator (TEG) that enables self-sustained electrical power generation under natural sunlight by establishing a system-level thermal configuration. The device consists of a W–MgF2 composite layer at the hot side and a paraffin-based composite containing SiO2, Al2O3, and BaTiO3 nanoparticles at the cold side, which operate cooperatively to maintain a stable temperature difference across the thermoelectric module. The W–MgF2 photothermal layer exhibits strong broadband solar absorption exceeding 75% up to 1500 nm and rapidly increases the hot-side temperature to approximately 67 °C under 1 sun illumination. In contrast, the paraffin-based composite suppresses heat accumulation at the cold side through selective mid-infrared emissivity together with enhanced thermal conductivity and thermal diffusivity, as supported by simulation results. As a result, a sustained temperature gradient of approximately 20 K is maintained across the device, leading to an output voltage of 5.7 mV under steady illumination. After electrical poling, the output voltage further increases to 6.2 mV without a noticeable change in the temperature gradient, indicating a polarization-assisted contribution from BaTiO3. Long-term operation confirms stable electrical output for more than 55 hr, demonstrating that the coupled photothermal heating and radiative cooling configuration effectively preserves the temperature gradient. Outdoor measurements, including operation in combination with a commercial aluminum heat sink, further confirm stable power generation and improved thermal management under practical operating conditions.
With growing interest in liquid–solid triboelectric platforms (L–S TEPs), research has predominantly optimized solid surfaces, leaving the role of liquid viscosity largely unexplored. Here, a pronounced viscosity dependence is revealed by comparing deionized water (low viscosity) and glycerol (high viscosity) under strictly controlled immersion-withdrawal motion. Glycerol forms a persistent liquid film on the solid surface during withdrawal, delaying detachment and prolonging the effective charge transfer duration relative to deionized water. Because charge transfer is governed by the evolution of liquid–solid contact and detachment, viscosity-controlled film retention offers an orthogonal strategy to mitigate output intermittency under low-frequency inputs in liquid–solid triboelectric nanogenerators. Moreover, the charge transfer duration correlates with rheometer-measured viscosity across glycerol-water mixtures, enabling proof-of-concept self-powered viscometry through machine-learning-assisted robust viscosity estimation. Overall, these results position viscosity as a key design parameter for engineering L–S TEP operation toward sustained energy harvesting and self-powered viscosity sensing.
Biodegradable porous zinc (Zn)–based scaffolds have emerged as promising temporary orthopedic implants due to their moderate degradation rate, essential physiological role, and intrinsic osteogenic, antibacterial, and immunomodulatory functions. Interconnected porous architectures that mimic trabecular bone are critical for enabling cell infiltration, vascularization, and bone ingrowth. However, increased porosity and specific surface area inevitably accelerate corrosion and Zn2+ release, giving rise to tightly coupled trade-offs among mechanical integrity, degradation behavior, cytocompatibility, antibacterial efficacy, and immune responses. This review presents a mechanism-oriented and integrative perspective on biodegradable porous Zn scaffolds, emphasizing the intrinsic coupling between scaffold architecture, corrosion kinetics, and the evolving biological microenvironment. State-of-the-art fabrication strategies—including powder metallurgy, additive manufacturing, electrodeposition, and pressure infiltration—are critically analyzed with respect to how fabrication-induced architectural features dictate mechanical performance, degradation evolution, and the spatiotemporal distribution of Zn2+ ions. Recent advances in Zn-mediated osteo-immunomodulation are synthesized, highlighting how Zn2+ and its degradation products regulate macrophage polarization and inflammatory signaling, thereby coordinating downstream osteogenesis, angiogenesis, and antibacterial activity. Finally, key challenges—including degradation–healing mismatch, excessive local Zn2+ accumulation, inflammatory risks, and limited osseointegration are discussed, and future directions are outlined toward multiscale architectural engineering, immune-instructive surface functionalization, and programmable degradation. This review positions porous Zn scaffolds as active, immune-regulating biomaterials and provides design principles for the development of next-generation biodegradable orthopedic implants.
Mechanical metamaterials emerge as architected materials that derive unprecedented properties from architecture rather than composition. Recently, attention has focused on multifunctional mechanical metamaterials (MMMs) that integrate multiple mechanical and physical functionalities within a single material system. This review presents a Mechano-X coupling overview of recent advances in MMMs. First, four representative architectural intelligences are categorized: lattice-based, origami-inspired, nonlinearity-embedded, and wave-governed MMMs. Deformation mechanisms, load-transfer pathways, and static–dynamic mechanical responses within these architectures collectively generate Mechano-X coupled multifunctionalities. Next, methodological advances for MMMs are reviewed, including topology optimization, machine learning-based prediction and generative artificial intelligence-powered inverse design, that enable demand-driven advancement and exploration. Then Mechano-X coupling paradigm is outlined, distinguishing mechanical–mechanical, mechanical-acoustic/wave, and mechanical-multiphysical couplings that allow simultaneous mechanical performance, wave manipulation, and multiphysical responses. Finally, the challenges and future directions regarding manufacturability, structural toughness, standardization, and sustainability are emphasized. Overall, MMMs represent an architectural intelligence that enables excellent performance, multifunctional integration, and on-demand tunability, thereby offering exceptional promise for advanced and practical engineering applications.
Optoelectronic neuromorphic computing systems have emerged to overcome the Von Neumann bottleneck by mimicking the structure and function of the human brain. These systems integrate sensing, memory, and computing within a single device, enabling low-power operation and fast processing speeds. Their operation is intertwined with synaptic plasticity and learning behavior, which are governed by intrinsic material properties and underpinned by distinctive light–matter interactions. In this study, we highlight emerging material platforms such as two-dimensional materials, perovskites, nanostructures, and conventional materials. Their superior optoelectronic performance and simple fabrication have facilitated the development of optical neuromorphic devices for both conventional neural networks and physical reservoir computing. In particular, physical reservoir computing exploits nonlinearity and fading-memory behavior, which distinguish it from conventional neural networks. Unlike traditional neural network that rely on static weight updates, reservoir computing uses system dynamics to compute and store temporal information. Recent demonstrations have exhibited real-time, low-power, and high-accuracy performance in diverse classification tasks, such as fingerprint recognition and human behavior analysis.
Flexible wireless-powered implantable medical devices (FW-IMDs) conform to biological tissues to minimize mechanical mismatch and inflammation compared to conventional rigid, battery-powered biomedical electronic systems, while maintaining stable, healthy bioelectronic interfaces. Their stretchable, bendable, and ultrathin form enables continuous deformation within dynamic organs while maintaining stable operation. Additionally, remote energy conversion technologies enable wireless power transmission and electric charge generation, offering promising subcutaneous applications such as powering rechargeable implantable bioelectronics and direct biotherapy. Although modern implantable batteries have achieved substantial miniaturization, their long lifespans still necessitate periodic replacement surgeries, which remain a major clinical burden. In this context, wireless power transfer (WPT) technologies provide a complementary solution by enabling non-surgical energy replenishment or continuous powering. This review summarizes the functions, materials, and architectures of the FW-IMDs. It functionally classifies these devices based on WPT systems, including near-field capacitive coupling, ultrasound-driven piezoelectric and triboelectric nanogenerators, light-mediated photovoltaic generators, and near-field inductive coupling. Particular emphasis is placed on integrating flexibility, biocompatibility, output enhancement, minimization, circuit integration, bioadhesiveness, and biodegradability. Finally, the review outlines current challenges and opportunities in clinical safety and advancement, and proposes future directions for hybrid, multifunctional, and adaptive WPT platforms, thereby presenting a coherent framework for FW-IMDs that operate reliably and sustainably within the human body.
