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As an inherent characteristic of light, polarization plays important roles in information storage, display and even encryption. Metasurfaces, composed of specifically designed subwavelength units in a two-dimensional plane, offer a great convenience for polarization manipulation, yet improving their integrability and broadband fidelity remain significant challenges. Here, based on the combination of various subwavelength cross-nanofins (CNs), a new type of metasurface for multichannel hybrid polarization distribution in near-field is proposed. Sub-wavelength CN units with various waveplate (WP) functionalities, such as frequency-division multiplexing WP, half-WP and quarter-WP are implemented with high efficiency in broadband. High-resolution grayscale image encryption, multi-image storage and rapid polarization detection are demonstrated by encoding the WP pixels into single, double and four channels, respectively. All these applications possess good fidelity in an ultrabroad wavelength band from 1.2 to 1.9 µm, and the high degree of integrability, easy fabrication and multifunction make the CN-shaped WP pixels a promising candidate in optical device miniaturization, quantum applications and imaging technologies.

Soft robots have significant advantages in flexibility and adaptability and have potential applications in the field of engineering. Unlike traditional manufacturing methods, three-dimensional (3D) printing provides a fast way to fabricate customized and multi-functional robots. However, the fabrication of soft robots requires multimaterial printers and the high-accuracy multi-step assembly process. Among them, fused deposition modeling (FDM) technology has taken the lead compared to other 3D printing methods due to its ease of use, accuracy, and repeatability. However, the FDM multimaterial printing has not been thoroughly explored. Here, we proposed a rigid and flexible material integrated printing approach based on FDM 3D printing technology and reported a cable-driven flexible pipe robot based on Yoshimura origami crease patterns. The implementations show that the robot can realize four-direction bending effectively by the corresponding drive control, which indicates the feasibility of our design and manufacturing method. The proposed approach paves an effective way to design and fabricate the rigid-flexible robot and other devices in the future. [ABSTRACT FROM AUTHOR]

Hollow microspheres as the filler material of syntactic foams have been adopted in extensive practical applications, where the physical parameters and their homogeneity have been proven to be critical factors during the design process, especially for high-specification scenarios. Based on double-emulsion droplet templates, hollow microspheres derived from microfluidics-enabled soft manufacturing have been validated to possess well-controlled morphology and composition with a much narrower size distribution and fewer defects compared to traditional production methods. However, for more stringent requirements, the innate density difference between the core–shell solution of the double-emulsion droplet template shall result in the wall thickness heterogeneity of the hollow microsphere, which will lead to unfavorable mechanical performance deviations. To clarify the specific mechanical response of microfluidics-derived hollow silica microspheres with varying eccentricities, a hybrid method combining experimental nanoindentation and a finite element method (FEM) simulation was proposed. The difference in eccentricity can determine the specific mechanical response of hollow microspheres during nanoindentation, including crack initiation and the evolution process, detailed fracture modes, load-bearing capacity, and energy dissipation capability, which should shed light on the necessity of optimizing the concentricity of double-emulsion droplets to improve the wall thickness homogeneity of hollow microspheres for better mechanical performance. [ABSTRACT FROM AUTHOR]

Highly stretchable and transparent ionic conducting materials enable electronic devices to have a distinguishable working mechanism and performances from the conventional electronics. Compared with hydrogels which contain large amounts of water to dissolve ions, ionic conductive elastomers (ICEs) are solvent‐free, and intrinsically immune from dehydration. However, the current manufacturing technologies constrain the ICE‐based ionotronics to simple and bulk geometries with single material, which greatly limits functionality and performance of ICEs‐based ionotronics. Herein, a stretchable ultraviolet curable ICEs (SUV‐ICEs) for 3D printing approach to fabricate complex 3D flexible electronics is reported. The developed SUV‐ICEs are highly stretchable and thermally stable. Using a self‐built DLP‐based 3D printer, that is able to print 3D flexible electronics consisting of SUV‐ICE covalently bonded with other dielectric elastomer, such as SUV‐ICE strain sensors, and a flexible mini‐keyboard. [ABSTRACT FROM AUTHOR]

Tailoring the electronic states of the dielectric oxide/diamond interface is critical to the development of next generation semiconductor devices like high-power high-frequency field-effect transistors. In this work, we investigate the electronic states of the TiO2/diamond 2 × 1–(100) interface by using first principles total energy calculations. Based on the calculation of the chemical potentials for the TiO2/diamond interface, it is observed that the hetero-interfaces with the C-OTi configuration or with two O vacancies are the most energetically favorable structures under the O-rich condition and under Ti-rich condition, respectively. The band structure and density of states of both TiO2/diamond and TiO2/H-diamond hetero-structures are calculated. It is revealed that there are considerable interface states at the interface of the anatase TiO2/diamond hetero-structure. By introducing H on the diamond surface, the interface states are significantly suppressed. A type-II alignment band structure is disclosed at the interface of the TiO2/diamond hetero-structure. The valence band offset increases from 0.6 to 1.7 eV when H is introduced at the TiO2/diamond interface. [ABSTRACT FROM AUTHOR]

Lower turn-on field (ETO) and threshold field (ETHR), as well as a higher current density, are desired characteristics of materials and structures for field emission (FE) applications. In this work, the properties of a boron-doped diamond (BDD) hollow nanoneedle array (HNNA) structure were remarkably enhanced through surface state modulation. By designedly controlling the surface roughness and boron concentration of the BDD film, a uniform and dense HNNA with a high aspect ratio (∼21.3) was constructed by applying O2 + Cl2 inductively coupled plasma reactive ion etching (ICP-RIE) for an optimal duration (90 min). Although the maximum HNNA density (∼5.5 × 106 mm–2) is produced at a shorter duration, the overall FE performance is even worse than that of the BDD film without an HNNA, arising from the field shielding effect and incomplete elimination of defective needles. The finally formed Actiniaria tentacle-like HNNA structure is associated with the masking role of oxidized Si and amorphous carbon on the top edge of the needle embryos, resulting from the electric field edge effect and Si supply accompanying the substrate. Meanwhile, the sp2 carbon generated by ICP-RIE on the surface of the as-etched HNNA promotes the FE, showing a minimum ETO of 0.11 V/μm. After moderate hydrogen plasma treatment, owing to the negative electron affinity (NEA) of C–H on p-type BDD with downward band bending of the conduction band minimum and local electric field enhancement induced by the hollow nanostructure, the hydrogen-terminated BDD–HNNA shows excellent FE stability and a linear Fowler–Nordheim relation with a lower ETO of 0.38 V/μm and ETHR of 2.21 V/μm and a desirable current density of 6532 μA/cm2 at 3.75 V/μm. The comprehensive FE properties of the surface-modulated high-quality BDD–HNNA exceed those of the vast majority of other conventional or popular nanostructural counterparts. [ABSTRACT FROM AUTHOR]

Vitrimers, a type of dynamically crosslinked polymers that combine the solvent‐ and heat‐resistance of thermosets with the reprocessability of thermoplastics, offer a new solution to the problem of plastic pollution. However, the current recycling approaches of vitrimers greatly constrain the shapes of recycled vitrimers to simple geometries, thus significantly limiting the application scopes of recycled vitrimers. Here, a simple but universal method for upcycling vitrimer wastes is reported by developing a UV curable recycling (UVR) solution system. Conventional unprintable vitrimer powders can be mixed with the UVR solution, and the resulting mixture is compatible with digital light processing based 3D printing to fabricate 3D structures with high resolution (up to 20 µm) and high geometric complexity. Heat treatment triggers bond exchange reactions in the printed structures, and greatly enhances the mechanical properties. This method allows to cyclically print vitrimer wastes multiple times. Moreover, the UVR‐vitrimer mixture solution can work as an adhesive to bond printed small parts together to build a larger and more complex structure which cannot be printed. The upcycling method reported in this work extends the application scope of recycled vitrimers and provide a practical solution to address environmental challenges associated with plastic pollution. [ABSTRACT FROM AUTHOR]

Chemical vapor deposited (CVD) diamond as a burgeoning multifunctional material with tailored quality and characteristics can be artificially synthesized and controlled for various applications. Correspondingly, the application-related “grade” concept associated with materials choice and design was gradually formulated, of which the availability and the performance are optimally suited. In this review, the explicit diversity of CVD diamond and the clarification of typical grades for applications, i.e., from resplendent gem-grade to promising quantum-grade, were systematically summarized and discussed, according to the crystal quality and main consideration of ubiquitous nitrogen impurity content as well as major applications. Realizations of those, from quantum-grade with near-ideal crystal to electronic-grade having extremely low imperfections and then to optical, thermal as well as mechanical-grade needing controlled flaws and allowable impurities, would competently fulfill the multi-field application prospects with appropriate choice in terms of cost and quality. Exceptionally, wide range defects and impurities in the gem-grade diamond (only indicating single crystal), which are detrimental for technology applications, endows CVD crystals with fancy colors to challenge their natural counterparts. [ABSTRACT FROM AUTHOR]