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"Avionics"
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Applications of Chromatic Confocal Technology in Precision Geometric Measurement of Workpieces
Chromatic confocal technology is increasingly applied in industries that require high-precision geometric measurements such as aerospace, naval ordnance, and medical electronics owing to its advantages in testing accuracy, real-time performance, anti-interference, and no damage to tested workpieces. This paper introduces the measurement principle of chromatic confocal technology and the structure of chromatic confocal sensors, and enumerates several typical application scenarios of the technology from the aspects of thickness measurement, profile, 3D topography scanning, roughness measurement, and wafer comprehensive parameter measurement. It also looks into potential development directions of chromatic confocal technology.
Journal Article
Strong sequentially bridged MXene sheets
Titanium carbide (Ti₃C₂Tₓ) MXene has great potential for use in aerospace and flexible electronics due to its excellent electrical conductivity and mechanical properties. However, the assembly of MXene nanosheets into macroscopic high-performance nanocomposites is challenging, limiting MXene’s practical applications. Here we describe our work fabricating strong and highly conductive MXene sheets through sequential bridging of hydrogen and ionic bonding. The ionic bonding agent decreases interplanar spacing and increases MXene nanosheet alignment, while the hydrogen bonding agent increases interplanar spacing and decreases MXene nanosheet alignment. Successive application of hydrogen and ionic bonding agents optimizes toughness, tensile strength, oxidation resistance in a humid environment, and resistance to sonication disintegration and mechanical abuse. The tensile strength of these MXene sheets reaches up to 436 MPa. The electrical conductivity and weight-normalized shielding efficiency are also as high as 2,988 S/cm and 58,929 dB·cm²/g, respectively. The toughening and strengthening mechanisms are revealed by molecular-dynamics simulations. Our sequential bridging strategy opens an avenue for the assembly of other high-performance MXene nanocomposites.
Journal Article
Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles
Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.
Journal Article
Universal inverse design of surfaces with thin nematic elastomer sheets
Programmable shape-shifting materials can take different physical forms to achieve multifunctionality in a dynamic and controllable manner. Although morphing a shape from 2D to 3D via programmed inhomogeneous local deformations has been demonstrated in various ways, the inverse problem—finding how to program a sheet in order for it to take an arbitrary desired 3D shape—is much harder yet critical to realize specific functions. Here, we address this inverse problem in thin liquid crystal elastomer (LCE) sheets, where the shape is preprogrammed by precise and local control of the molecular orientation of the liquid crystal monomers. We show how blueprints for arbitrary surface geometries can be generated using approximate numerical methods and how local extrinsic curvatures can be generated to assist in properly converting these geometries into shapes. Backed by faithfully alignable and rapidly lockable LCE chemistry, we precisely embed our designs in LCE sheets using advanced top-down microfabrication techniques. We thus successfully produce flat sheets that, upon thermal activation, take an arbitrary desired shape, such as a face. The general design principles presented here for creating an arbitrary 3D shape will allow for exploration of unmet needs in flexible electronics, metamaterials, aerospace and medical devices, and more.
Journal Article
Additive Manufacturing of Polymer Materials: Progress, Promise and Challenges
The use of additive manufacturing (AM) has moved well beyond prototyping and has been established as a highly versatile manufacturing method with demonstrated potential to completely transform traditional manufacturing in the future. In this paper, a comprehensive review and critical analyses of the recent advances and achievements in the field of different AM processes for polymers, their composites and nanocomposites, elastomers and multi materials, shape memory polymers and thermo-responsive materials are presented. Moreover, their applications in different fields such as bio-medical, electronics, textiles, and aerospace industries are also discussed. We conclude the article with an account of further research needs and future perspectives of AM process with polymeric materials.
Journal Article
Analytical study on university programs in the field of drones and avionics in the European area
This article presents a comparative analysis of university programs across Europe that focus on drone architecture and avionics. The aim of the analysis is to identify best practices, trends, and relevant development directions to support the update of the curriculum at Moldova State University. By comparing the structure, content, and orientation of these programs, the study seeks to align the educational offering with current labor market demands and sustainability requirements.
Journal Article
Energy storage emerging
Energy storage is an integral part of modern society. A contemporary example is the lithium (Li)-ion battery, which enabled the launch of the personal electronics revolution in 1991 and the first commercial electric vehicles in 2010. Most recently, Li-ion batteries have expanded into the electricity grid to firm variable renewable generation, increasing the efficiency and effectiveness of transmission and distribution. Important applications continue to emerge including decarbonization of heavy-duty vehicles, rail, maritime shipping, and aviation and the growth of renewable electricity and storage on the grid. This perspective compares energy storage needs and priorities in 2010 with those now and those emerging over the next few decades. The diversity of demands for energy storage requires a diversity of purpose-built batteries designed to meet disparate applications. Advances in the frontier of battery research to achieve transformative performance spanning energy and power density, capacity, charge/discharge times, cost, lifetime, and safety are highlighted, along with strategic research refinements made by the Joint Center for Energy Storage Research (JCESR) and the broader community to accommodate the changing storage needs and priorities. Innovative experimental tools with higher spatial and temporal resolution, in situ and operando characterization, first-principles simulation, high throughput computation, machine learning, and artificial intelligence work collectively to reveal the origins of the electrochemical phenomena that enable new means of energy storage. This knowledge allows a constructionist approach to materials, chemistries, and architectures, where each atom or molecule plays a prescribed role in realizing batteries with unique performance profiles suitable for emergent demands.
Journal Article
High-specific-power flexible transition metal dichalcogenide solar cells
Semiconducting transition metal dichalcogenides (TMDs) are promising for flexible high-specific-power photovoltaics due to their ultrahigh optical absorption coefficients, desirable band gaps and self-passivated surfaces. However, challenges such as Fermi-level pinning at the metal contact–TMD interface and the inapplicability of traditional doping schemes have prevented most TMD solar cells from exceeding 2% power conversion efficiency (PCE). In addition, fabrication on flexible substrates tends to contaminate or damage TMD interfaces, further reducing performance. Here, we address these fundamental issues by employing: (1) transparent graphene contacts to mitigate Fermi-level pinning, (2) MoO
x
capping for doping, passivation and anti-reflection, and (3) a clean, non-damaging direct transfer method to realize devices on lightweight flexible polyimide substrates. These lead to record PCE of 5.1% and record specific power of 4.4 W g
−1
for flexible TMD (WSe
2
) solar cells, the latter on par with prevailing thin-film solar technologies cadmium telluride, copper indium gallium selenide, amorphous silicon and III-Vs. We further project that TMD solar cells could achieve specific power up to 46 W g
−1
, creating unprecedented opportunities in a broad range of industries from aerospace to wearable and implantable electronics.
Ultrathin transition metal dichalcogenides (TMDs) hold promise for next-generation lightweight photovoltaics. Here, the authors demonstrate the first flexible high power-per-weight TMD solar cells with notably improved power conversion efficiency.
Journal Article
Graphene oxide bulk material reinforced by heterophase platelets with multiscale interface crosslinking
Graphene oxide (GO) and reduced GO possess robust mechanical, electrical and chemical properties. Their nanocomposites have been extensively explored for applications in diverse fields. However, due to the high flexibility and weak interlayer interactions of GO nanosheets, the flexural mechanical properties of GO-based composites, especially in bulk materials, are largely constrained, which hinders their performance in practical applications. Here, inspired by the amorphous/crystalline feature of the heterophase within nacreous platelets, we present a centimetre-sized, GO-based bulk material consisting of building blocks of GO and amorphous/crystalline leaf-like MnO
2
hexagon nanosheets adhered together with polymer-based crosslinkers. These building blocks are stacked and hot-pressed with further crosslinking between the layers to form a GO/MnO
2
-based layered (GML) bulk material. The resultant GML bulk material exhibits a flexural strength of 231.2 MPa. Moreover, the material exhibits sufficient fracture toughness and strong impact resistance while being light in weight. Experimental and numerical analyses indicate that the ordered heterophase structure and synergetic crosslinking interactions across multiscale interfaces lead to the superior mechanical properties of the material. These results are expected to provide insights into the design of structural materials and potential applications of high-performance GO-based bulk materials in aerospace, biomedicine and electronics.
A nacre-inspired, centimetre-sized bulk material is prepared by assembling graphene oxide and microscale amorphous/crystalline heterophase reinforcing platelets adhered together with polymer-based crosslinkers, which shows high flexural strength and fracture toughness.
Journal Article