Zinc and its alloys are promising biodegradable materials for orthopedic implants, but simultaneously enhancing strength and ductility remains challenging. In this study, laser powder bed fusion technology was employed to fabricate zinc-copper (Zn–Cu) alloy implants. Within the optimized processing window, increasing the laser energy density elevated the melt pool temperature and provided sufficient thermodynamic conditions for grain growth, whereas decreasing the energy density accelerated cooling and suppressed grain coarsening. By grouping multiple layers and alternately applying high and low energy densities between groups, a heterostructure with alternating coarse- and fine-grained layers was constructed. These heterostructured Zn–Cu alloys exhibited an ultimate tensile strength of (245.6 ± 8.7) MPa and a ductility of (12.7 ± 0.9)%, demonstrating a remarkable strength-ductility synergy among LPBF-processed Zn-based alloys. Mechanical analysis revealed that heterodeformation-induced stress, interlayer dislocations, and the inhibition of strain localization collectively contributed to the superior mechanical performance. Additionally, the heterostructured Zn–Cu alloys exhibited typical gradient degradation characteristics and outstanding osteogenic activity, highlighting their potential for load-bearing biodegradable orthopedic applications. This work establishes a process-microstructure-property paradigm for LPBF of Zn alloys and offers a generalizable strategy for designing high-performance biodegradable metal implants.
Abstract Robotic vision serves as a crucial sensing modality in perception for artificial intelligence (AI), enabling mobile robots to recognize their environments with human-level intelligence. However, conventional complementary metal-oxide-semiconductor (CMOS) image sensors are not ideal for mobile robotic vision, because their planar form factor necessitates bulky and heavy optical assemblies and power- and time-intensive corrective computations. Bio-inspired vision systems, enabled by the advent of curved image sensors, provide optimal solutions for mobile robotics, enabling AI-friendly imaging functionalities without compromising mobility. In this review, we summarize recent advances in bio-inspired vision systems, with a special focus on curved image sensors and their biologically motivated implementations in robotic vision systems. We first introduce fabrication strategies for curved image sensors—an essential yet technically challenging component of bio-inspired vision systems—in terms of material-level engineering, mechanically compliant device designs, and curved integration techniques. We then review bio-inspired vision systems based on curved image sensors, highlighting their unique optical configurations, advanced imaging functionalities, and AI-integrated robotic applications. Therefore, a system-level framework that connects curvature-enabled optics, mechanically adaptive sensor architectures, and AI-compatible sensing strategies is provided. Finally, we outline the key challenges that hinder the practical deployment of bio-inspired vision systems and discuss promising future research directions toward their integration into mobile robotic platforms.
Abstract The in-situ reconstruction of mineralized matrices within curved joint defects plays a crucial regulatory role in the functional recovery and homeostasis of surrounding soft tissues. However, achieving this with current therapeutic devices remains challenging. Inspired by the development process in natural tissues from the ossification centers (OCs), a patient-specific joint repair device capable of adapting to the curved joint defects and regulating the regeneration of bone mineralized matrices was developed by encoding mineralized microrobots abundant in nucleation sites via a 4D bioprinting strategy integrated with finite element analysis. The skeleton of the microrobots, prepared using a microfluidic-ice template technique, closely resembled the OCs organic matrix in both appearance and network structure. By incorporating polyphenol, the skeleton can sequentially stabilize calcium phosphate precursors via cation−π interactions to confer osteoinductive properties, bind Fe3O4 nanoparticles through coordination interactions, and facilitate cell loading, thereby forming locatable osteoinductive microrobots. By formulating microrobots as bioinks and pre-planning printing schemes based on differences in bioink expansion, devices with deformed shapes tailored to specific requirements, and driven by an external magnetic field to calibrate their position, can be customized through a finite element analysis-integrated 4D bioprinting strategy. Owing to the high water content, the devices were clearly visible in both proton density and T2-weighted magnetic resonance imaging modes. In the printed devices, the microcomponents promoted osteogenic differentiation of cells by up-regulating focal adhesion and extracellular matrix-receptor interaction signaling pathways, and enriching mineralization precursors, thereby controllably regulating bone mineralized matrix generation in the heterogeneous devices. This work presents a new concept for the engineering and manufacturing of personalized curved joint defect repair devices.
Abstract With their high carrier mobility and large surface area, two-dimensional (2D) materials are ideal electrodes for various micro-energy storage devices enabling advanced on-chip power for integrated electronics. However, the miniaturization of micro-energy storage devices based on 2D materials remains constrained by the challenges in high-throughput patterning of high-resolution electrodes and reliable integration across diverse substrates. Here, we reported a Janus-mask-defined printing method to pattern high-resolution MXene electrodes. The Janus mask, with its asymmetric wettability, enables effective control over Ti3C2Tx MXene ink flow, resulting in uniform electrode micro-patterns that are sharp and continuous. As a result, the patternable feature size of the electrodes was improved from the millimeter scale to 80 μm. The high-resolution electrodes can be transferred onto diverse substrates via a capillary-assisted transfer process. With a LiTFSI-based polymer electrolyte, the assembled micro-supercapacitor (MSC) exhibits a high areal capacitance of 4.57 mF cm-2 and a volumetric capacitance of 169.23 F cm-3. The volumetric energy density reaches 76.72 mWh cm-3, which outperforms most reported MXene-based MSCs. We also integrated a flexible MSC module as an on-chip power source for a force sensor, producing a self-powered sensor system. This work provides an effective route for high-resolution patterning and scalable transfer of a broad range of nanomaterials beyond MXenes.
Abstract Abstract: With the continuous scaling of semiconductor process nodes, wafer defect detection faces stringent sensitivity requirements. Conventional far-field optical methods remain constrained by the diffraction limit, low signal-to-noise ratio (SNR), and limited imaging contrast, hindering efficient, non-destructive detection of nanoscale defects. To overcome these limitations, we propose a three-dimensional imaging approach based on anisotropic topological charge migration (ATCM). The system employs visible-wavelength ±1st-order vortex beams as the illumination source. Through sample-beam interaction, topological charge migration generates orbital angular momentum (OAM) signals containing 0th-order and high-order components. By spatially filtering out high-order OAM components via complementary aperture slits, defect-specific signals are effectively isolated from background noise. Coupled with active dark-line modulation, the system achieves directional selectivity, enabling enhancement or suppression of oriented structures. Experimentally, ATCM significantly suppresses regular background interference, realizes high-contrast imaging of 25 nm break-to-bridge defects, and detects 10 nm gold nanoparticles with high SNR. The system also provides 3D tomographic imaging, allowing accurate spatial localization of defects. Moreover, we demonstrate the potential of ATCM for label-free bioimaging, achieving high-SNR visualization of cellular and subcellular structures in tissue sections and single cells without staining. This work establishes a high-sensitivity, 3D-resolved inspection tool not only for semiconductor metrology but also for life sciences, showing promise for non-destructive testing and dynamic observation at the nanoscale.
As micro/nanoelectromechanical systems (MEMS/NEMS) advance toward higher integration, device fabrication is entering the era of atomic and close-to-atomic scale manufacturing (ACSM). Interface friction has emerged as a critical factor affecting device performance and reliability. Atomic-scale friction is jointly determined by the atomic structure, surface chemistry, and quantum effects, exhibiting behavior markedly different from macroscopic friction. This paper reviews recent advances in atomic-scale friction research, systematically summarizing major friction models and the influence of interatomic interactions, van der Waals forces, interfacial charge transfer, and energy dissipation mechanisms (phonon friction and electronic friction) on friction behavior. It also summarizes the primary physical mechanisms enabling ultra-low friction in two-dimensional (2D) materials, carbon materials, and semiconductor materials while introducing relevant experimental methods, simulation techniques, and the application of artificial intelligence (AI) in friction research. This paper aims to provide a clear framework for understanding and controlling friction mechanisms at the atomic scale, offering theoretical and methodological references for designing highly reliable micro/nano devices and novel quantum devices.
The fabrication of unsupported three-dimensional (3D) metal microstructures is essential for advanced electronic interconnects and three-dimensional circuitry. Low-melting-point alloys (LMPAs) are attractive for additive manufacturing due to their high electrical conductivity and low processing temperature; however, their high surface tension and surface oxide layer result in poor wettability and unstable deposition, limiting printing resolution and three-dimensional formability. Here, we report a printing technique for Field’s metal (FM) driven by the synergistic effect of electrowetting and tension. By dynamically regulating the wetting behavior between the FM and the substrate, stable extrusion through microscale nozzles is achieved, enabling controllable deposition. High-resolution two-dimensional (2D) patterns with line widths ranging from 20 to 200 μm can be printed over a wide speed window from 0.1 to >100 mm·s ^−1 , allowing flexible control of pattern dimensions. Enhanced wetting behavior improves the interfacial stability of the printed two-dimensional features during subsequent tension-driven three-dimensional construction, enabling resistance to localized detachment under tension. This stability ensures the reliable fabrication of three-dimensional structures on diverse substrates, particularly curved surfaces. Using this method, various unsupported 3D structures, including helical lines, microelectrode arrays, and spatial circuits, were fabricated on substrates with different curvatures, all of which exhibited excellent electrical conductivity (2 × 10 ^4 S·cm ^−1 ). The printed three-dimensional structures remain mechanically stable under inertial loading up to 0.5 g and structurally intact during thermal cycling from 0 to 65 °C, demonstrating reliable performance for practical applications. These capabilities demonstrate the applicability of this technique for three-dimensional electrical interconnects, vertical conductive vias, wireless power transmission components, and spatially integrated electronic circuits.
Organic materials that exhibit gradient conductance plasticity are currently regarded as promising candidates to play the key role of bionic synapses in flexible neuromorphic circuits, mimicking brain-like processing behavior. However, owing to their poor long-term operating stability, low intrinsic conductivity, and inferior charge transfer ability, their electronic synaptic applications are largely restricted. Herein, we controllably synthesized a two-dimensional (2D) flake-like hydrogen-bonded organic framework composed of meso-tetra(carboxyphenyl) porphyrin monomers (TCPP-HOF), which serves as a reliable synaptic medium with high material stability and enhanced charge-carrier transportation. An all-solution-processed 10 × 10 2D MXene/TCPP-HOF/MXene/polyimine (PI) heterostructured flexible device array using MXene as the electrode and PI as the substrate is fabricated, presenting gradient conductance modulation under both continuous electrical scanning and pulse algorithms, closely simulating biological synaptic behaviors. More importantly, such a metal-electrode-free device is easily degradable, giving the possibility of recyclable transient electronics and information security. This work sets a precedent for the development of highly viable HOF-manipulated artificial synaptic mimicry for low-cost, easily processed, and highly efficient neuromorphic applications.
Polymer nanocomposites filled with highly thermally conductive nano/microparticles have shown promise for efficient thermal management in power electronics due to their excellent flexibility and thermal conductivity. However, it remains challenging to align particulate fillers into an optimal heat transfer path through a fast and large-scale green fabrication process, especially when adapting to various types of fillers and flexible matrices. Herein, we report a unique rolled sonication-enabled microstructure orientation (RSMO) method that enables superfast densification and orientation of various fillers in polymers through the synergistic thermo-mechanical effects of high-frequency vibration with roller pressing, achieving full processing within one second without external heating. Ultrasound-induced dense packing and oriented structures synergistically enhance both thermal conductivity (an increase of 171%) and tensile strength (19-fold enhancement) compared with simple roller pressing. RSMO has been demonstrated to be applicable to a wide range of fillers, including metals, inorganic nonmetals, and organic materials, as well as various film-forming techniques, such as electrospinning and screen printing. We successfully fabricated large-area thermally conductive films using RSMO and demonstrated their thermal management capabilities in power electronics and flexible thermoelectric generation, thereby confirming their significant potential in preparing high-performance thermal management materials for flexible electronic devices.
Magnetostrictive polycrystalline Fe–Ga alloys have sparked widespread interest owing to their remarkable magnetic–mechanical coupling characteristics, but always suffer bottlenecks in concurrent structure-performance customization, which is essential for high-performance engineering applications. Herein, laser-beam powder bed fusion (LPBF) process featuring an interlayer rotation strategy was proposed in this study for the integrated manufacturing of high-performance and customized geometry for polycrystalline Fe–Ga alloys. On the one hand, fine magnetostrictive Fe–Ga alloys with complex geometries were first manufactured to overcome the geometric limitations of magnetostrictive components. On the other hand, the interlayer rotation strategy enabled localized customization of thermal distribution during the solidification process and thereby the in-situ modulation of grain growth and defect evolution. Specifically, the LPBF strategy effectively promoted surface planarization, stress relief, and defect healing, and significant reductions in both porosity (from 2.29% to 0.29%) and residual stress (from 319 MPa to 66 MPa) were eventually achieved within the LPBF-manufactured Fe–Ga alloys based on computed tomography (CT) and X-ray stress analysis. Moreover, the LPBF-manufactured polycrystalline Fe–Ga alloys exhibited a unique {001}< 100> cube texture according to the crystal self-alignment mechanism. As a result, the strong cube texture, together with high densification and relieved stress, contributed to an optimal combination of high magnetostriction ((118 ± 5) × 10 ^−6 ) and low coercivity ((8.6 ± 0.4) Oe) in the LPBF-manufactured polycrystalline Fe–Ga alloys. These findings demonstrated a prospective approach for in-situ texture and defect modulation as well as complex geometric manufacturing of magnetostrictive Fe–Ga alloys, providing a basis for developing next-generation magnetostrictive devices with customized geometry–structure–performance integration.
Heterogeneous material 3D printing (HM3DP) represents a transformative approach in additive manufacturing, enabling precise spatial control over material composition, microstructure, and functionality. This technology transcends the limitations of homogeneous fabrication by integrating multi-material systems, dynamic process programming, and external field modulation, offering innovative solutions for biomimetic structures, flexible electronics, and smart devices. This review systematically examines the chemical foundations, process innovations, and applications of HM3DP and proposes a three-tier classification system—composition, structure, and functional–temporal heterogeneity—to standardize evaluation metrics. Key challenges, including dynamic interface compatibility, cross-scale heterogeneous mechanical integrity and fracture control, and functional–temporal synergy, are critically analyzed. Future directions emphasize multi-physics collaboration and intelligent optimization to achieve adaptive, high-performance heterogeneous systems. HM3DP is poised to bridge the gap between static manufacturing and dynamic, intelligent design, unlocking new frontiers in materials science and engineering.
Atomic-level manufacturing represents the ultimate frontier in materials science, promising unprecedented control over the composition and structure of matter. However, conventional fabrication techniques often face limitations in terms of scalability, energy efficiency, and applicability to non-layered materials. Liquid metal (LM) printing has recently emerged as a disruptive alternative, leveraging the unique physicochemical properties of liquid metals, including high fluidity, self-limiting surface oxidation, and compositional tunability, to synthesize and transfer atomically thin films under ambient conditions. This review provides a comprehensive overview of LM printing for the fabrication of two-dimensional (2D) metal-based materials and devices. We begin by elucidating the fundamental principles of atomic-level manufacturing and the distinctive advantages of liquid metals. We then systematically detail a diverse toolkit of LM printing techniques, including gas injection, laser-assisted, spin-coating, scraping, roller-based, squeeze-printing, and direct touch methods. The synthesis of a broad library of atomically thin materials, encompassing oxides, sulfides, nitrides, and phosphates derived from Ga, In, Sn, Bi, Zn, and their multi-component alloys, is thoroughly reviewed. Furthermore, we explore the integration of these 2D materials into high-performance devices such as transistors, photodetectors, sensors, memristors, and neuromorphic electronics. Finally, we discuss the existing challenges and future outlooks for this burgeoning field, highlighting pathways toward autonomous, scalable, and truly atomic-level manufacturing paradigms.
The transient thermal cycling characteristics during laser powder bed fusion (LPBF) induce elemental segregation and columnar growth, resulting in significant mechanical anisotropy and strength–ductility trade-off in titanium alloys. In order to break through this bottleneck, this work proposes a strategy of inducing equiaxation of columnar grains through recrystallization and regulating the morphology of the α″ phase (from an acicular shape to nanoparticles) to synergistically optimize the uniformity, strength and ductility of LPBF-fabricated Ti-35Nb-5Cu- x Mo (Ti355 x, x = 0, 1, 2, 4 wt%) alloys. The results demonstrate that LPBF-fabricated Ti355 x alloys display equiaxed/columnar microstructures with significant mechanical anisotropy and strength–ductility trade-off. After tailored solution heat treatment at 950 ℃, the Ti3552 alloy (HT950-Ti3552) achieves chemical homogenization and thermally driven equiaxation of columnar grains, leading to excellent isotropic mechanical properties. Concurrently, the morphology of α″ is transformed from an acicular-shaped to nanoparticle. As a result, the interactions between dislocations and α″ nanoparticles promote cross slip, thereby homogenizing plastic flow and delivering high ductility (>25%) for the HT950-Ti3552 alloys during tensile deformation. Moreover, the addition of Mo increases the dislocation density and enhances the solute drag effect, leading to refined β grains and α″ nanoparticles, which in turn increase the yield strength (YS) of the HT950‐Ti3552 alloy by about 90 MPa compared to that of the HT950‐Ti355 alloy. This work establishes a theoretical basis and technical route for developing LPBF-fabricated β-type titanium alloys with isotropic mechanical properties and an improved balance between strength and ductility.
Abstract Maintaining thermal comfort is vital for human health, productivity and overall well-being. Conventional heating, ventilation and air-conditioning (HVAC) systems, while effective, are energy-intensive and poorly tailored to individual physiology. Wearable personalized heating and cooling technologies offer a complementary route by providing targeted, skin-level thermal regulation that can reduce the load on ambient HVAC and enable local comfort control. This review presents a mechanistic and quantitative overview of wearable thermal management (WTM) technologies, organized into active, passive and hybrid systems. Representative active devices based on Joule heating and thermoelectric (TE) modules deliver local skin cooling of approximately 5–11 °C (and up to ∼16 °C in clinical fever scenarios) and heating increases of 10–40 °C above ambient temperature, typically at sub-watt to few-watt power levels. Passive approaches employing bio-based phase change materials (PCMs, latent heat on the order of 100–200 J·g −1 ), insulative aerogels and radiative cooling (RC) textiles achieve 3–10 °C cooling relative to conventional fabrics without external power. Hybrid strategies combine these elements to extend comfort duration and broaden the operating envelope while moderating energy consumption. Furthermore, this review highlights advances in smart materials for WTM, including bio-based and encapsulated PCMs, positive temperature coefficient (PTC) composites for self-regulating heating, high-conductivity graphene and MXene-based films, flexible TE modules and bio-inspired textiles. A particular emphasis is placed on emerging intelligent control paradigms, where physiological sensing, artificial intelligence (AI)-driven comfort models and neuromorphic thermal circuits enable predictive, low-power and user-specific regulation. Applications span medical thermotherapy and fever management, protection in extreme occupational environments, athletic performance and recovery, immersive virtual/augmented reality (VR/AR) and everyday comfort. Finally, the review outlines key commercialization pathways and current challenges, including textile-compatible manufacturing (weaving, coating and printing), requirements for breathability, washability and long-term durability, and the need for standardized testing and regulatory frameworks. These perspectives define concrete milestones for translating laboratory prototypes into safe, sustainable and scalable WTM products.
