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Rapid On-Chip Healing of Metal Thin Films
摘要： Self-healing behavior, the ability to autonomously counteract damage, is observed in some inorganic materials, and it has recently been extended to various artificial systems. In metals, healing usually requires thermal activation by a furnace treatment that stimulates damage repair. High temperature exposure, however, renders these routes incompatible with temperature-sensitive systems such as on-chip microelectronic components. In this work, designing Ni/Al multilayers as on-chip heat sources, a concept for on-demand healing of metal films that no longer relies on external annealing, is demonstrated. The process is based on harvesting a solitary self-sustained heat wave that is produced by a solid-state reaction in the heat source to weld cracks in different metal films. Healing is activated at room temperature with a remarkably small current input and in situ probing reveals a large conductance recovery up to 500 nm wide cracks within 1 ms, orders of magnitude faster than furnace-based approaches. Intrinsic heat source healing represents a unique concept for rapid on-chip healing of metal films that will provide new flexibility to prevent failure in inaccessible electronic systems: from implantable healthcare devices, to space probe instrumentation.
关键词： reactive multilayers,self-healing,intrinsic heat source,thin films
更新于2025-09-23 15:21:01
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Infrared Cameras in Electronics Development
摘要： There has been a distinct trend in electronics development in the last few years: Packing density is increasing. Today, modern smartphones are much more powerful than they were only a few years ago, yet they are no bigger. The same applies to IT devices, automobile electronics, and consumer electronics. Accordingly, problems caused by heating must be looked out for with great care. Modern infrared measurement technology is an important aid in this regard.
关键词： electronics development,heat dissipation,Infrared cameras,semiconductor devices,temperature measurement,power loss
更新于2025-09-23 15:21:01
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Self-propelled water droplet movement on a laser-etched radial gradient copper surface
摘要： This paper reports the behavior of water droplets on a topography-based, radial gradient on a metallic surface. The radial gradient was designed to concentrate water in the center region through the spontaneous motion and coalescence of individual droplets on the gradient pattern. In this work, parallel microchannels having a fixed width (~25 μm) and depth (100 μm) but variable spacing were used to impart a net surface tension force to the droplet for actuation. The diameter of the radial gradient (i.e. circular test region) was approximately 18.9 mm (or, ~0.75 in.). The surfaces were fabricated using a 355 nm YVO4 laser system and then characterized using droplet injection (5–38 μL) and spray testing techniques. Injected droplets were observed to move spontaneously away from the hydrophobic outer ring region of the circle towards the hydrophilic center as designed by the gradient. Droplet travel distances as large as 4 mm were measured depending on the droplet volume and injection site location. In application, such a design could be useful for promoting droplet coalescence on a surface and subsequently removal by gravity through the formation of sufficiently large droplets from two or more otherwise small droplets.
关键词： Surface tension gradient,Microchannels,Condensation,Heat exchangers,Radial pattern,Laser etching,Water droplet
更新于2025-09-23 15:21:01
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Design and investigation of cooling system for high-power LED luminaire
摘要： This paper is concerned with development of cooling system for high-power LED luminaire, including design, simulation, production and investigation. Dimension, shape, and topology optimization algorithms and their program realization are developed with the use of MathCad. Thermal design by Comsol Multiphysics showed that the system on the base of heat pipes is the most effective system for cooling of high-power LED luminaire. The numerical simulation was employed to valid the designed-in engineering solution of cooling system for high-power LED luminaire under elevated temperature operating conditions and different orientation in space. In accordance to simulation data cooling system on the base of heat pipes is designed. Theoretical results are well validated by experimental data and numerical simulation and can be widely utilized for designing of cooling system related to various LED products.
关键词： Cooling system,Heat pipe,Thermal design,High-power LED luminaire
更新于2025-09-23 15:21:01
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An optimized phosphor model coupled with thermal and optical behavior and a thereof ring-shaped phosphor convertor for improving thermal uniformity in laser illuminations
摘要： Due to the high energy density of laser diode (LD), the ?uorescent convertor always su?ers from serious overheating problems, such as thermal quenching, signi?cant e?ciency drop or even material carbonization failure. In this work, we improved the current optical-thermal model by coupling the optical behavior of red (nitride)/yellow (YAG) phosphor and thermal conductivity of di?erent hybrid particles concentrations. According to the theoretical analysis, the thermal sensitive concentration zone was revealed. To avoid the hotspot occurs, a ring-shaped phosphor convertor with two di?erent concentrations was developed. Results showed that the convertor with high-concentration center could reduce the max temperature by 9.4% without obvious optical power loss. Some further research suggestions were also proposed to improve the thermal performances of the laser illumination.
关键词： Thermal management,Phosphor heat generation,Theoretical model,Laser illumination
更新于2025-09-23 15:21:01
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Analysis of the Mechanical Behavior of AISI 4340 Steel Cylindrical Specimens Heat Treated with Fiber Laser
摘要： This paper describes a method for analyzing and improving mechanical behavior of a cylindrical workpiece made of AISI 4340 steel, by its heat treatment with a 3kW fiber laser source. Research and expertise acquired in recent years have shown that improving the mechanical properties of AISI 4340 steel by heat treatment significantly reduces the design dimensions and thus optimizes the final weight of the product. Understanding the impact that a laser heat treatment can have on mechanical properties and the fatigue life can lead to significantly optimizing the design dimensions. This research investigates the effect and control of laser heat treatment parameters to optimize the mechanical behavior of an AISI 4340 steel cylindrical standard-specimen, which has a diameter of the calibrated part of 9.00-mm. The control of the case depth and its uniformization were guided by experimental and numerical modeling. Tensile tests, fatigue tests (hysteresis loops), microhardness, optical microscopy, and scanning electron microscopy measurements were used to evaluate each condition of the experimental design. Results indicate that laser heat treatment increases fatigue endurance by more than 20% compared to non-hardened samples. Moreover, it is shown with a model of neural prediction, and a rigorous analysis of variance, that the numerical values of the mechanical properties are in direct agreement with the laser hardening input parameters.
关键词： Fiber laser,Fatigue endurance,AISI 4340 steel,Mechanical behavior,Heat treatment
更新于2025-09-23 15:21:01
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Damp-Heat-Stable, High-Efficiency, Industrial-Size Silicon Heterojunction Solar Cells
摘要： Silicon heterojunction (SHJ) solar cells hold the power conversion efficiency (PCE) record among crystalline solar cells. However, amorphous silicon is a typical high-entropy metastable material. Damp-heat aging experiments unveil that the amorphous/crystalline silicon interface is susceptible to moisture, which is potentially the biggest stumbling block for mass production. By capping SiNx and SiOx dielectrics, the absolute PCE degradation is predicted to be only (cid:1)0.6% after a 30-year installation. This demonstrates the SHJ solar cell is a highly promising candidate for next-generation photovoltaics.
关键词： High efficiency,Amorphous silicon,Mass production,Damp-heat stability,Silicon heterojunction solar cells
更新于2025-09-23 15:21:01
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Fabrication and characterization of graphene quantum dots thin film for reducing cross-sectional heat transfer through smart window
摘要： Graphene and its derivatives have been reported as materials with excellent electrical and thermal conductivity, allowing for various promising applications. In particular, the large-scale surface coating of graphene-based materials can be employed to minimize cross-sectional heat transfer through the glass window. This study introduces a facile and cost-effective method to fabricate graphene quantum dots (GQDs) thin film on Fluorine-doped Tin Oxide (FTO) glass via casting of the GQDs dispersion and stabilizing with poly-vinyl-pyrrolidone (PVP). The thin film possesses excellent optical properties of GQDs and allows more than 80 % of visible transmittance. The presence of the GQDs thin film shows effective reduction in the cross-sectional thermal diffusivity of FTO glass, from 0.55 mm2/s to zero when measured with laser flash over a 4-second period. This low cost and eco-friendly GQDs thin film will be a promising material for heat management in smart window applications.
关键词： Smart window,Cross-Sectional heat transfer,Graphene quantum dots,Poly-Vinyl-Pyrrolidone,Visible transmittance
更新于2025-09-23 15:21:01
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Thermal and optical properties of high-density GaN micro-LED arrays on flexible substrates
摘要： Flexible GaN-based micron-size light-emitting diodes (μLEDs) with high brightness and low power-consumption are a promising technology for next-generation wearable displays. While, integrating GaN μLEDs onto flex can provide more functionality, the bending-induced strain and potential self-heating of the device are the challenges that degrade the device performance on plastic platforms. Here, a novel “paste-and-cut” approach to selectively transfer GaN μLEDs from sapphire substrates onto flexible platforms demonstrated the effectiveness of various intermediate metallic-bonding layers and LED geometries on the optical properties and performance of the flexible devices. Computational thermal simulation of the flexible μLEDs showed effective heat dissipation for devices mounted on plastic platforms bonded using a 0.5 μm thick Cu metallic pad to create stable optical emission (λ = 450 nm) under current densities of > 1 A/cm2. Through a finite-element analysis (FEA), it was determined that the applied stress-induced strain near the quantum wells of the μLEDs can be negligible for devices with diameters smaller than 20 microns. Experimental verification supported the simulation results; the diodes were found to be electrically and thermally stable when copper electrode layers > 600 nm thick was used to bond the LEDs onto the plastic platforms. The I-V characteristics of the μLEDs showed no measurable degradation after transfer onto the flexible substrate with a turn-on voltage of 2.5 V. Commensurate to the FEA simulations, no measurable optical wavelength shift was observed for LED having a diameter of 20 microns when driven at a current density of 1 A/cm2 under different mechanical strain.
关键词： Flexible Display,Heat Transfer,Invariant Emission,GaN Micro-LED
更新于2025-09-23 15:21:01
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Photo-Thermoelectric Conversion of Plasmonic Nanohole Array
摘要： Plasmonic photo-thermoelectric conversion offers an alternative photodetection mechanism that is not restricted by semiconductor bandgaps. Here, we report a plasmonic photodetector consisting of an ultra-thin silver film with nanohole array, whose photodetection mechanism is based on thermoelectric conversion triggered by plasmonic local heating. The detector exhibits a maximum photocurrent at the wavelength of the surface plasmon polaritons, determined by the periodicity of the nanoholes. Hence, the response wavelength of the detector can be controlled via the morphological parameters of the nanohole pattern. The contribution of plasmonic local heating to thermoelectric conversion is verified experimentally and numerically, enabling discussion on the mechanisms governing light detection. These results provide a starting point for the development of other nanoscale photodetectors.
关键词： plasmon,photodetector,silver film,plasmonic local heat,thermoelectric conversion,nanohole
更新于2025-09-23 15:21:01