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Invisibility cloaks that can suppress wave scattering by objects have attracted a tremendous amount of interest in the past two decades. In comparison to prior methods that were severely limited by narrow bandwidths, here we present a practical strategy to suppress sound scattering across an ultra-broad spectrum by leveraging illusion metamaterials. Consisting of a collection of subwavelength tunnels with precisely crafted internal structures, this illusion metamaterial has the ability to guide acoustic waves around the obstacles and accurately recreate the incoming wavefront on the exit surface. Remarkably, two ultra-broadband illusionary effects are produced, disappearing space and time shift. Sound scatterings are removed at all frequencies below a limit determined by the tunnel width, as confirmed by full-wave simulations and acoustic experiments. Our strategy represents a universal approach to solve the key bottleneck of bandwidth limitation in the field of cloaking in transmission, and establishes a metamaterial platform that enables the long-desired ultra-broadband sound manipulation such as acoustic camouflage and reverberation control, opening up exciting new possibilities in practical applications., (© 2024. The Author(s).)

Artificial skins or flexible pressure sensors that mimic human cutaneous mechanoreceptors transduce tactile stimuli to quantitative electrical signals. Conventional trial-and-error designs for such devices follow a forward structure-to-property routine, which is usually time-consuming and determines one possible solution in one run. Data-driven inverse design can precisely target desired functions while showing far higher productivity, however, it is still absent for flexible pressure sensors because of the difficulties in acquiring a large amount of data. Here, we report a property-to-structure inverse design of flexible pressure sensors, exhibiting a significantly greater efficiency than the conventional routine. We use a reduced-order model that analytically constrains the design scope and an iterative "jumping-selection" method together with a surrogate model that enhances data screening. As an exemplary scenario, hundreds of solutions that overcome the intrinsic signal saturation have been predicted by the inverse method, validating for a variety of material systems. The success in property design on multiple indicators demonstrates that the proposed inverse design is an efficient and powerful tool to target multifarious applications of flexible pressure sensors, which can potentially advance the fields of intelligent robots, advanced healthcare, and human-machine interfaces., Competing Interests: Competing interests statement:The authors declare no competing interest.

The long-standing paradox between matte appearance and transparency has deprived traditional matte materials of optical transparency. Here, we present a solution to this centuries-old optical conundrum by harnessing the potential of disordered optical metasurfaces. Through the construction of a random array of meta-atoms tailored in asymmetric backgrounds, we have created transparent matte surfaces that maintain clear transparency regardless of the strength of disordered light scattering or their matte appearances. This remarkable property originates in the achievement of highly asymmetric light diffusion, exhibiting substantial diffusion in reflection and negligible diffusion in transmission across the entire visible spectrum. By fabricating macroscopic samples of such metasurfaces through industrial lithography, we have experimentally demonstrated transparent windows camouflaged as traditional matte materials, as well as transparent displays with high clarity, full color, and one-way visibility. Our work introduces an unprecedented frontier of transparent matte materials in optics, offering unprecedented opportunities and applications.

Incorporating a negative feedback loop in a synthetic material to enable complex self-regulative behaviours akin to living organisms remains a design challenge. Here we show that a hydrogel-based vehicle can follow the directions of photonic illumination with directional regulation inside a constraint-free, fluidic space. By manipulating the customized photothermal nanoparticles and the microscale pores in the polymeric matrix, we achieved strong chemomechanical deformation of the soft material. The vehicle swiftly assumes an optimal pose and creates directional flow around itself, which it follows to achieve robust full-space phototaxis. In addition, this phototaxis enables a series of complex underwater locomotions. We demonstrate that this versatility is generated by the synergy of photothermofluidic interactions resulting in closed-loop self-control and fast reconfigurability. The untethered, electronics-free, ambient-powered hydrogel vehicle manoeuvres through obstacles agilely, following illumination cues of moderate intensities, similar to that of natural sunlight., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Multiple sclerosis (MS), a chronic neurodegenerative disease driven by damage to the protective myelin sheath, is currently incurable. Today, all clinically available treatments modulate the immune-mediated symptoms of the disease but they fail to stop neurodegeneration in many patients. Remyelination, the regenerative process of myelin repair by oligodendrocytes, which is considered a necessary step to protect demyelinated axons and stop neuronal death, is impaired in MS patients. One of the major obstacles to finding effective remyelinating drugs is the lack of biomimetic drug screening platforms that enable quantification of compounds' potential to stimulate 3D myelination in the physiologically relevant axon-like environment. To address this need, we built a unique myelination drug discovery platform, by expanding our previously developed technology, artificial axons (AAs), which enables 3D-printing of synthetic axon mimics with the geometry and mechanical properties closely resembling those of biological axons. This platform allows for high-throughput phenotypic myelination assay based on quantification of 3D wrapping of myelin membrane around axons in response to compounds. Here, we demonstrate quantification of 3D myelin wrapping by rat oligodendrocytes around the axon mimics in response to a small library of known pro-myelinating compounds. This assay shows pro-myelinating activity for all tested compounds consistent with the published in vitro and in vivo data, demonstrating predictive power of AA platform. We find that stimulation of myelin wrapping by these compounds is dose-dependent, providing a facile means to quantify the compounds' potency and efficacy in promoting myelin wrapping. Further, the ranking of relative efficacy among these compounds differs in this 3D axon-like environment as compared to a traditional oligodendrocyte 2D differentiation assay quantifying area of deposited myelin membrane. Together, we demonstrate that the artificial axons platform and associated phenotypic myelin wrapping assay afford direct evaluation of myelin wrapping by oligodendrocytes in response to soluble compounds in an axon-like environment, providing a predictive tool for the discovery of remyelinating therapies., (© 2023. The Author(s).)

Fast oxygen reduction reaction (ORR) at the cathode is a key requirement for the realization of low-temperature solid oxide fuel cells (SOFCs). While the design of three-dimensional (3D) structures has emerged as a new and promising approach to improving the electrochemical performance of SOFC cathodes, achieving versatile structures and structural stability is still challenging. In this study, we demonstrate a novel architectural design for a superior cathode with fast ORR activity. By employing a completely new fabrication process comprising a 3D printing technique and pulsed laser deposition (PLD), we design 3D La 0.8 Sr 0.2 CoO 3-δ (LSC) micro-nano structures with the desired shape. 3D-printed yttria-stabilized ZrO 2 (YSZ) microstructures significantly increase the ratio of surface area to volume while maintaining suitable ionic conductivity comparable to that of single-crystalline YSZ substrates. Scanning electron microscopy and energy dispersive X-ray microanalysis reveal the formation of crack- or void-free YSZ microstructures and the uniform deposition of LSC films by PLD on the YSZ microstructures. The 3D LSC micro-nano structures show significantly enhanced oxygen surface exchange coefficients ( k chem ) extracted from electrical conductivity relaxation (ECR) measurements by up to 3 orders of magnitude relative to the bulk LSC. Furthermore, electrochemical impedance spectroscopy measurements verify the k chem values from ECR and no directional difference in the measured ORR activity depending on the shape of 3D microstructures. The dramatic enhancement of the ORR activity of LSC is attributed to the increased film surface areas resulting from the 3D YSZ microstructures.

Background: Toxigenic Corynebacterium ulcerans is an emerging zoonosis globally, causing both cutaneous and respiratory diphtheria-like illness. In Queensland, human infection with toxigenic C. ulcerans is rare, with only three cases reported before October 2015. This case series describes five subsequent cases of toxigenic C. ulcerans in Queensland with links to companion animals., Methods: All data were collected as part of routine public health response, and strains were whole genome sequenced for further characterisation. Household contacts were screened, treated with appropriate antibiotics, and received a diphtheria toxoid-containing vaccine if more than five years had elapsed since their last dose., Findings: No epidemiological or genomic links could be established between any of the five patients, including between the two cases notified from the same locality within eight days of each other. The C. ulcerans strains from Cases Two, Four and Five were closely related to the strains isolated from their respective pets by whole genome sequencing. Domestic dogs were identified as the most likely mode of transmission for Cases One and Three; however, this was unable to be laboratory confirmed, since Case One's dog was treated with antibiotics before it could be tested, and Case Three's dog was euthanised and cremated prior to case notification., Interpretation: These are the first reported Australian cases of this emerging zoonosis with links to companion animals. These cases demonstrate the likely transmission route between companion animals and humans, with no evidence of human-to-human transmission. The existing requirement in the Queensland Health Public Health Management Guidelines, of restrictions on cases and some contacts while awaiting swab results, is currently under review., (© Commonwealth of Australia CC BY-NC-ND)

3D printing of hydrogels has been widely explored for the rapid fabrication of complex soft structures and devices. However, using 3D printing to customize hydrogels with both adequate adhesiveness and toughness remains a fundamental challenge. Here, we demonstrate mussel-inspired (polydopamine) PDA hydrogel through the incorporation of a classical double network (2-acrylamido-2-methylpropanesulfonic acid) PAMPS/(polyacrylamide) PAAm to achieve simultaneously tailored adhesiveness, toughness, and biocompatibility and validate the 3D printability of such a hydrogel into customized architectures. The strategy of combining PDA with PAMPS/PAAm hydrogels leads to favorable adhesion on either hydrophilic or hydrophobic surfaces. The hydrogel also shows excellent flexibility, which is attributed to the reversible cross-linking of PDA and PAMPS, together with the long-chain PAAm cross-linking network. Among them, the reversible cross-linking of PDA and PAMPS is capable of dissipating mechanical energy under deformation. Meanwhile, the long-chain PAAm network contributes to maintaining a high deformation capability. We establish a theoretical framework to quantify the contribution of the interpenetrating networks to the overall toughness of the hydrogel, which also provides guidance for the rational design of materials with the desired properties. Our work manifests a new paradigm of printing adhesive, tough, and biocompatible interpenetrating network hydrogels to meet the requirements of broad potential applications in biomedical engineering, soft robotics, and intelligent and superabsorbent devices.

The main challenge in preparing a flexible mold stamp using roll-to-roll nanoimprint lithography is to simultaneously increase the imprintable area with a minimized perceptible seam. However, the current methods for stitching multiple small molds to fabricate large-area molds and functional surfaces typically rely on the alignment mark, which inevitably produces a clear alignment mark and stitched seam. In this study, we propose a mark-less alignment by the pattern itself method inspired by moiré technique, which uses the Fourier spectral analysis of moiré patterns formed by superposed identical patterns for alignment. This method is capable of fabricating scalable functional surfaces and imprint molds with quasi-seamless and alignment mark-free patterning. By harnessing the rotational invariance property in the Fourier transform, our approach is confirmed to be a simple and efficient method for extracting the rotational and translational offsets in overlapped periodic or nonperiodic patterns with a minimized stitched region, thereby allowing for the large-area and quasi-seamless fabrication of imprinting molds and functional surfaces, such as liquid-repellent film and micro-optical sheets, that surpass the conventional alignment and stitching limits and potentially expand their application in producing large-area metasurfaces., (© 2023. The Author(s).)

A new variant of Streptococcus pyogenes serotype M1 (designated 'M1 UK ') has been reported in the United Kingdom, linked with seasonal scarlet fever surges, marked increase in invasive infections, and exhibiting enhanced expression of the superantigen SpeA. The progenitor S. pyogenes 'M1 global ' and M1 UK clones can be differentiated by 27 SNPs and 4 indels, yet the mechanism for speA upregulation is unknown. Here we investigate the previously unappreciated expansion of M1 UK in Australia, now isolated from the majority of serious infections caused by serotype M1 S. pyogenes. M1 UK sub-lineages circulating in Australia also contain a novel toxin repertoire associated with epidemic scarlet fever causing S. pyogenes in Asia. A single SNP in the 5' transcriptional leader sequence of the transfer-messenger RNA gene ssrA drives enhanced SpeA superantigen expression as a result of ssrA terminator read-through in the M1 UK lineage. This represents a previously unappreciated mechanism of toxin expression and urges enhanced international surveillance., (© 2023. The Author(s).)

Acoustic metamaterials have been widely investigated over the past few decades and have realized acoustic parameters that are not achievable using conventional materials. After demonstrating that locally resonant acoustic metamaterials are capable of acting as subwavelength unit cells, researchers have evaluated the possibility of breaking the classical limitations of the material mass density and bulk modulus. Combined with theoretical analysis, additive manufacturing and engineering applications, acoustic metamaterials have demonstrated extraordinary capabilities, including negative refraction, cloaking, beam formation and super-resolution imaging. Owing to the complexity of impedance boundaries and mode transitions, there are still challenges in freely manipulating acoustic propagation in an underwater environment. This review summarizes the developments in underwater acoustic metamaterials over the past 20 years, which include underwater acoustic invisibility cloaking, underwater beam formation, underwater metasurfaces and phase engineering, underwater topological acoustics and underwater acoustic metamaterial absorbers. With the evolution of underwater metamaterials and the timeline of scientific advances, underwater acoustic metamaterials have demonstrated exciting applications in underwater resource development, target recognition, imaging, noise reduction, navigation and communication., (© The Author(s) 2022. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

Visualizing hydrogenation processes in palladium (Pd) in real-time is important to various hydrogen-involved applications. However, observing hydrogen diffusion of Pd was limited by its small permittivity variation, and the kinetics of lateral diffusion of hydrogen in Pd film was not reported. Here, we proposed an optical microscopy-based visualization of Pd hydrogenation from the diffusion surface to the interior by introducing a fast-response mechanical platform that transforms the hydrogen diffusion into self-organized ordered wrinkles with sharp optical contrast. This platform is a Au/Pd double layer on an elastomer, which results in directional hydrogenation from the sidewall to the interior. The kinetics of hydrogenation in the interior of the palladium along the diffusion direction was monitored in real-time. This platform will enable in situ visualization of atom/ion diffusion on metals that are crucial in energy storage and hydrogen detection.

Membrane-on-chip is of growing interest in a wide variety of high-throughput environmental and water research. Advances in membrane technology continuously provide novel materials and multi-functional structures. Yet, the incorporation of membrane into microfluidic devices remains challenging, thus limiting its versatile utilization. Herein, via micro-stereolithography 3D printing, we propose and fabricate a "fish gill" structure-integrated on-chip membrane device, which has the self-sealing attribute at structure-membrane interface without extra assembling. As a demonstration, metallic micromesh and polymeric membrane can also be easily embedded in 3D printed on-chip device to achieve anti-fouling and anti-clogging functionality for wastewater filtration. As evidenced from in-situ visualization of structure-fluid-foulant interactions during filtration process, the proposed approach successfully adopts the fish feeding mechanism, being able to "ricochet" foulant particles or droplets through hydrodynamic manipulation. When benchmarked with two common wastewater treatment scenarios, such as plastic micro-particles and emulsified oil droplets, our biomimetic filtration devices exhibit 2 ~ 3 times longer durability for high-flux filtration than devices with commercial membrane. This proposed 3D printing-on-membrane approach, elegantly bridging the fields of microfluidics and membrane science, is instrumental to many other applications in energy, sensing, analytical chemistry and biomedical engineering., (© 2022. The Author(s).)

To address current unmet needs in terms of scalability and material biocompatibility for future photocrosslinking-based additive manufacturing technologies, emergent platform designs are in inexorable demand. In particular, a shift from the present use of cell-damaging UV light sources in light-based three-dimensional (3D) bioprinting methods demands new platforms. We adopted an organic light-emitting diode (OLED) microdisplay as a digital visible light modulator to create a 3D printing platform modality that offers scalability and multi-material capability while forgoing the need for UV photocrosslinking. We formulate biocompatible inks that are visible light-crosslinkable with relatively quick photoinitiation rates. We demonstrated successful attachment and rapid growth of primary human dermal fibroblast-adult (HDF-a) cells on biological substrates fabricated using the OLED platform. This platform incites new possibilities by providing a simple-yet-effective means for low-cost, high-throughput, and multi-material 3D fabrication of functional structures made of polymers, ceramic composites, and biomaterials., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

Evaporation-induced particle aggregation in drying droplets is of significant importance in the prevention of pathogen transfer due to the possibility of indirect fomite transmission of the infectious virus particles. In this study, particle aggregation was directionally controlled using contact line dynamics (pinned or slipping) and geometrical gradients on microstructured surfaces by the systematic investigation of the evaporation process on sessile droplets and sprayed microdroplets laden with virus-simulant nanoparticles. Using this mechanism, we designed robust particle capture surfaces by significantly inhibiting the contact transfer of particles from fomite surfaces. For the proof-of-concept, interconnected hexagonal and inverted pyramidal microwall were fabricated using ultraviolet-based nanoimprint lithography, which is considered to be a promising scalable manufacturing process. We demonstrated the potentials of an engineered microcavity surface to limit the contact transfer of particle aggregates deposited with the evaporation of microdroplets by 93% for hexagonal microwall and by 96% for inverted pyramidal microwall. The particle capture potential of the interconnected microstructures was also investigated using biological particles, including adenoviruses and lung-derived extracellular vesicles. The findings indicate that the proposed microstructured surfaces can reduce the indirect fomite transmission of highly infectious agents, including norovirus, rotavirus, or SARS-CoV-2, via respiratory droplets.

Microphysiological systems (MPS), comprising human cell cultured in formats that capture features of the three-dimensional (3D) microenvironments of native human organs under microperfusion, are promising tools for biomedical research. Here we report the development of a mesoscale physiological system (MePS) enabling the long-term 3D perfused culture of primary human hepatocytes at scales of over 10 6 cells per MPS. A central feature of the MePS, which employs a commercially-available multiwell bioreactor for perfusion, is a novel scaffold comprising a dense network of nano- and micro-porous polymer channels, designed to provide appropriate convective and diffusive mass transfer of oxygen and other nutrients while maintaining physiological values of shear stress. The scaffold design is realized by a high resolution stereolithography fabrication process employing a novel resin. This new culture system sustains mesoscopic hepatic tissue-like cultures with greater hepatic functionality (assessed by albumin and urea synthesis, and CYP3A4 activity) and lower inflammation markers compared to comparable cultures on the commercial polystyrene scaffold. To illustrate applications to disease modeling, we established an insulin-resistant phenotype by exposing liver cells to hyperglycemic and hyperinsulinemic media. Future applications of the MePS include the co-culture of hepatocytes with resident immune cells and the integration with multiple organs to model complex liver-associated diseases., (Creative Commons Attribution license.)

The limitation of projection microstereolithography in additive manufacturing methods is that they typically use a single-aperture imaging configuration, which restricts their ability to produce microstructures in large volumes owing to the trade-off between image resolution and image field area. Here, we propose an integral lithography based on integral image reconstruction coupled with a planar lens array. The individual microlenses maintain a high numerical aperture and are used to create digital light patterns that can expand the printable area by the number of microlenses (10 3 to 10 4 ), thereby allowing for the scalable stereolithographic fabrication of 3D features that surpass the resolution-to-area scaling limit. We extend the capability of integral lithography for programmable printing of deterministic nonperiodic structures through the rotational overlapping or stacking of multiple exposures with controlled angular offsets. This printing platform provides new possibilities for producing periodic and aperiodic microarchitectures spanning four orders of magnitude from micrometers to centimeters.

Direct Ink Writing (DIW) has demonstrated great potential as a versatile method to 3D print multifunctional structures. In this work, we report the implementation of hydrogel meta-structures using DIW at room temperature, which seamlessly integrate large specific surface areas, interconnected porous characteristics, mechanical toughness, biocompatibility, and water absorption and retention capabilities. Robust but hydrophobic polymers and weakly crosslinked nature-origin hydrogels form a balance in the self-supporting ink, allowing us to directly print complex meta-structures without sacrificial materials and heating extrusion. Mechanically, the mixed bending or stretching of symmetrical re-entrant cellular lattices and the unique curvature patterns are combined to provide little lateral expansion and large compressive energy absorbance when external forces are applied on the printed meta-structures. In addition, we have successfully demonstrated ear, aortic valve conduits and hierarchical architectures. We anticipate that the reported 3D meta-structured hydrogel would offer a new strategy to develop functional biomaterials for tissue engineering applications in the future., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Authors.)

In this Letter, we theoretically propose and experimentally demonstrate a three-dimensional soundproof acoustic cage structure, hereby denoted as an acoustic metacage. The metacage is composed of six acoustic metamaterial slabs with open holes and hidden bypass space coiling tunnels connected to the holes. Band structure analysis reveals a novel physical mechanism to open a low-frequency broad partial band gap via the band folding in other directions, which can also be interpreted by an effective medium with indefinite effective mass density and negative effective modulus. Transmission loss in simulations and in the acoustic impedance tube are administered. Strikingly, we prove that the soundproofing effect of the metacage is robust against the airflow perturbation induced by a fan. Our work paves a road for low-frequency airborne soundproof structures in the presence of ventilation.

Electrodermal devices that capture the physiological response of skin are crucial for monitoring vital signals, but they often require convoluted layered designs with either electronic or ionic active materials relying on complicated synthesis procedures, encapsulation, and packaging techniques. Here, we report that the ionic transport in living systems can provide a simple mode of iontronic sensing and bypass the need of artificial ionic materials. A simple skin-electrode mechanosensing structure (SEMS) is constructed, exhibiting high pressure-resolution and spatial-resolution, being capable of feeling touch and detecting weak physiological signals such as fingertip pulse under different skin humidity. Our mechanical analysis reveals the critical role of instability in high-aspect-ratio microstructures on sensing. We further demonstrate pressure mapping with millimeter-spatial-resolution using a fully textile SEMS-based glove. The simplicity and reliability of SEMS hold great promise of diverse healthcare applications, such as pulse detection and recovering the sensory capability in patients with tactile dysfunction., (© 2021. The Author(s).)

Artificial liquid-repellent surfaces inspired by biomimetic structures provide a wide range of functional surfaces for various practical applications, such as self-cleaning, antisticking, oil/water separation, and droplet manipulation. However, functional biomimetic structures cannot be fabricated using conventional techniques. For example, mushroom-like topologies on the skin of springtails, which are referred to as "doubly reentrant structures," have attracted significant attention owing to their extraordinary liquid-repellent properties. Current methods of fabricating these reentrant structures have several limitations, such as complex material systems, processing steps, and additional chemical treatments. This study proposed a simple micro-shape-deformed approach to fabricate mushroom-like reentrant structures by digital light processing, a three-dimensional (3D) printing technique, with volumetric shrinkage. The nonuniform cross-linking process and light propagation during photopolymerization caused the deformation of the topological patterns atop the micropillar arrays, resulting in bent structures for mushroom-like shape-deformed microarchitectures. This 3D-printed shape-deformed microstructure exhibits a highly stable liquid repellency without perfluorinated coatings.

Objective: This meta-analysis aimed to systematically review the effects of etomidate (ETM) during anesthetic induction on patients undergoing cardiac surgery., Design: Systematic review and meta-analysis., Setting: Operating room., Participants: Patients undergoing cardiac surgery., Interventions: ETM or control drugs., Measurements and Main Results: PubMed, Cochrane Library, OVID, and EMBASE were searched through August 31, 2020. Primary outcomes included hemodynamic profiles and stress responses. Secondary outcomes included morbidity, mortality, and postoperative recovery. For continuous/dichotomous variables, treatment effects were calculated as weighted mean difference (WMD)/odds ratio (OR) and 95% confidence interval (CI). A database search yielded 18 randomized controlled trials including 1,241 patients. The present meta-analysis demonstrated that ETM-anesthetized patients had lower heart rates (WMD, -3.31; 95% CI -5.43 to -1.19; p = 0.002), higher blood pressures (systolic blood pressure: WMD, 12.02; 95% CI 6.24 to 17.80; p < 0.0001; diastolic blood pressure: WMD, 5.23; 95% CI 2.39 to 8.08; p = 0.0003; mean arterial pressure (MAP): WMD, 8.64; 95% CI 5.85 to 11.43; p < 0.00001), less requirement for vasopressor (OR, 0.26; 95% CI 0.15 to 0.44; p < 0.00001), and more nitroglycerin usage (OR, 14.89; 95% CI 4.92 to 45.08; p < 0.00001) during anesthetic induction. Current meta-analysis also demonstrated that single-dose ETM lowered cortisol levels transiently and did not have a significant effect on endogenous norepinephrine and epinephrine levels and was not associated with increased postoperative inotrope and/or vasopressor requirement. Additionally, the meta-analysis suggested that ETM anesthesia was associated with neither increased mortality nor morbidity, except a higher incidence of transient adrenal insufficiency in ETM recipients., Conclusion: The present meta-analysis suggested that single-dose ETM during anesthetic induction could be associated with more stable hemodynamics, transient and reversible lower cortisol levels, and a higher adrenal insufficiency incidence, but not worse outcomes in cardiac surgical patients., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Advances in development of artificial muscles have enabled creation of soft robots with biological dexterity and self-adaption in unstructured environments; however, production of scalable artificial muscles with multiple-mode actuations remains elusive. Inspired by muscle-fiber arrays in muscular hydrostats, we present a class of versatile artificial muscles called MAIPAMs (muscle-fiber array inspired pneumatic artificial muscles), capable of multiple-mode actuations (such as parallel elongation-bending-spiraling actuations, 10 parallel bending actuations and cascaded elongation-bending-spiraling actuations). Our MAIPAMs consist of active 3D elastomer-balloon arrays reinforced by a passive elastomer membrane, achieved through a planar design and one-step rolling fabrication approach. We introduce prototypical designs for the MAIPAMs and demonstrate their muscle-mimic structures and versatility, as well as their scalable ability to integrate flexible but non-stretchable layers for contraction and twisting actuation modes and compliant electrodes for self-sensing. We further demonstrate that this class of artificial muscles shows potential for versatile robotic applications, such as carrying a camera for recording videos, gripping or manipulating objects, and climbing a pipe-line., (© The Author(s) 2021. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

This paper presents a method to characterize the effective properties of inertial acoustic metamaterial unit cells for underwater operation. The method is manifested by a fast and reliable parameter retrieval procedure utilizing both numerical simulations and measurements. The effectiveness of the method was proved to be self-consistent by a metamaterial unit cell composed of aluminum honeycomb panels with soft rubber spacers. Simulated results agree well with the measured responses of this metamaterial in a water-filled resonator tube. A sub-unity density ratio and an anisotropic mass density are simultaneously achieved by the metamaterial unit cell, making it useful in implementations of transformation acoustics. The metamaterial, together with the approach for its characterization, are expected to be useful for underwater acoustic devices.

Kirigami, with facile and automated fashion of three-dimensional (3D) transformations, offers an unconventional approach for realizing cutting-edge optical nano-electromechanical systems. Here, we demonstrate an on-chip and electromechanically reconfigurable nano-kirigami with optical functionalities. The nano-electromechanical system is built on an Au/SiO 2 /Si substrate and operated via attractive electrostatic forces between the top gold nanostructure and bottom silicon substrate. Large-range nano-kirigami like 3D deformations are clearly observed and reversibly engineered, with scalable pitch size down to 0.975 μm. Broadband nonresonant and narrowband resonant optical reconfigurations are achieved at visible and near-infrared wavelengths, respectively, with a high modulation contrast up to 494%. On-chip modulation of optical helicity is further demonstrated in submicron nano-kirigami at near-infrared wavelengths. Such small-size and high-contrast reconfigurable optical nano-kirigami provides advanced methodologies and platforms for versatile on-chip manipulation of light at nanoscale.

The mechanical properties of engineering structures continuously weaken during service life because of material fatigue or degradation. By contrast, living organisms are able to strengthen their mechanical properties by regenerating parts of their structures. For example, plants strengthen their cell structures by transforming photosynthesis-produced glucose into stiff polysaccharides. In this work, we realize hybrid materials that use photosynthesis of embedded chloroplasts to remodel their microstructures. These materials can be used to three-dimensionally (3D)-print functional structures, which are endowed with matrix-strengthening and crack healing when exposed to white light. The mechanism relies on a 3D-printable polymer that allows for an additional cross-linking reaction with photosynthesis-produced glucose in the material bulk or on the interface. The remodeling behavior can be suspended by freezing chloroplasts, regulated by mechanical preloads, and reversed by environmental cues. This work opens the door for the design of hybrid synthetic-living materials, for applications such as smart composites, lightweight structures, and soft robotics., Competing Interests: Competing interest statement: The University of Southern California has filed a patent application related to the work described here.

To maximize energy transmission from a source through a media, the concept of impedance matching has been established in electrical, acoustic, and optical engineering. However, existing design of acoustic impedance matching, which extends exactly by a quarter wavelength, sets a fundamental limit of narrowband transmission. Here, we report a previously unknown class of bioinspired metagel impedance transformers to overcome this limit. The transformer embeds a two-dimensional metamaterial matrix of steel cylinders into hydrogel. Using experimental data of the biosonar from the Indo-Pacific humpback dolphin, we demonstrate through theoretical analysis that broadband transmission is achieved when the bioinspired acoustic impedance function is introduced. Furthermore, we experimentally show that the metagel device offers efficient implementation in broadband underwater ultrasound detection with the benefit of being soft and tunable. The bioinspired two-dimensional metagel breaks the length-wavelength dependence, which paves a previously unexplored way for designing next-generation broadband impedance matching devices in diverse wave engineering., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

3D printing has become one of the most promising methods to construct delicate 3D structures. However, precision and material utilization efficiency are limited. Here, we propose a one-droplet 3D printing strategy to fabricate controllable 3D structures from a single droplet ascribing to the receding property of the three-phase contact line (TCL) of the resin droplet. The well-controlled dewetting force of liquid resin on the cured structure results in the minimization of liquid residue and the high wet and net material utilization efficiency in forming a droplet into a 3D structure. Additionally, extra curing induced protruding or stepped sidewalls under high printing speed, which require high UV intensity, can be prevented. The critical is the free contact surface property of the droplet system with the introduction of the receding TCL, which increased the inner droplet liquid circulation and reduces the adhesion properties among the liquid resin, cured resin, and resin vat.

Deep learning (DL) has been applied extensively in many computational imaging problems, often leading to superior performance over traditional iterative approaches. However, two important questions remain largely unanswered: first, how well can the trained neural network generalize to objects very different from the ones in training? This is particularly important in practice, since large-scale annotated examples similar to those of interest are often not available during training. Second, has the trained neural network learnt the underlying (inverse) physics model, or has it merely done something trivial, such as memorizing the examples or point-wise pattern matching? This pertains to the interpretability of machine-learning based algorithms. In this work, we use the Phase Extraction Neural Network (PhENN) [Optica 4, 1117-1125 (2017)], a deep neural network (DNN) for quantitative phase retrieval in a lensless phase imaging system as the standard platform and show that the two questions are related and share a common crux: the choice of the training examples. Moreover, we connect the strength of the regularization effect imposed by a training set to the training process with the Shannon entropy of images in the dataset. That is, the higher the entropy of the training images, the weaker the regularization effect can be imposed. We also discover that weaker regularization effect leads to better learning of the underlying propagation model, i.e. the weak object transfer function, applicable for weakly scattering objects under the weak object approximation. Finally, simulation and experimental results show that better cross-domain generalization performance can be achieved if DNN is trained on a higher-entropy database, e.g. the ImageNet, than if the same DNN is trained on a lower-entropy database, e.g. MNIST, as the former allows the underlying physics model be learned better than the latter.

Objective Post-operative cognitive dysfunction (POCD) and post-operative delirium (POD) are two common post-operative cerebral complications. The current meta-analysis was to systematically review the effects of penehyclidine hydrochloride (PHC) on POCD and POD in surgical patients.Methods Electronic databases were searched to identify all randomized controlled trials comparing PHC with atropine/scopolamine/placebo on POCD and POD in surgical patients. Primary outcomes of interest included the incidences of POCD and POD; the secondary outcomes of interest included peri-operative mini-mental state examination (MMSE) scores. Two authors independently extracted peri-operative data, including patients' baseline characteristics, surgical variables, and outcome data. For dichotomous data (POCD and POD occurrence), treatment effects were calculated as odds ratio ( OR ) and 95% confidential interval ( CI ). Each outcome was tested for heterogeneity, and randomized-effects or fixed-effects model was used in the presence or absence of significant heterogeneity. For continuous variables (MMSE scores), treatment effects were calculated as weighted mean difference (WMD) and 95% CI . Statistical significance was defined as P <0.05.Results Our search yielded 33 studies including 4017 patients. Meta-analysis showed that, the incidence of POCD in PHC group was comparable to that in saline group ( OR =0.97; 95% CI : 0.58-1.64; P =0.92), scopolamine group ( OR =0.78; 95% CI : 0.48-1.27; P =0.32) and atropine group ( OR =1.20; 95% CI : 0.86-1.67; P =0.29). The incidence of POD in PHC group was comparable to that in saline group ( OR =1.53; 95% CI : 0.81-2.90; P =0.19) and scopolamine group ( OR =0.53; 95% CI : 0.06-4.56; P =0.56), but higher than that in atropine group ( OR =4.49; 95% CI : 1.34-15.01; P =0.01).Conclusions PHC premedication was not associated with increased incidences of POCD or POD as compared to either scopolamine or placebo.

Background: Ulinastatin is a type of glycoprotein and a nonspecific wide-spectrum protease inhibitor like antifibrinolytic agent aprotinin. Whether Ulinastatin has similar beneficial effects on blood conservation in cardiac surgical patients as aprotinin remains undetermined. Therefore, a systematic review and meta-analysis were performed to evaluate the effects of Ulinastatin on perioperative bleeding and transfusion in patients who underwent cardiac surgery., Methods: Electronic databases were searched to identify all clinical trials comparing Ulinastatin with placebo/blank on postoperative bleeding and transfusion in patients undergoing cardiac surgery. Primary outcomes included perioperative blood loss, blood transfusion, postoperative re-exploration for bleeding. Secondary outcomes include perioperative hemoglobin level, platelet counts and functions, coagulation tests, inflammatory cytokines level, and so on. For continuous variables, treatment effects were calculated as weighted mean difference (WMD) and 95% confidential interval (CI). For dichotomous data, treatment effects were calculated as odds ratio and 95% CI. Statistical significance was defined as P < .05., Results: Our search yielded 21 studies including 1310 patients, and 617 patients were allocated into Ulinastatin group and 693 into Control (placebo/blank) group. There was no significant difference in intraoperative bleeding volume, postoperative re-exploration for bleeding incidence, intraoperative red blood cell transfusion units, postoperative fresh frozen plasma transfusion volumes and platelet concentrates transfusion units between the 2 groups (all P > .05). Ulinastatin reduces postoperative bleeding (WMD = -0.73, 95% CI: -1.17 to -0.28, P = .001) and red blood cell (RBC) transfusion (WMD = -0.70, 95% CI: -1.26 to -0.14, P = .01), inhibits hyperfibrinolysis as manifested by lower level of postoperative D-dimer (WMD = -0.87, 95% CI: -1.34 to -0.39, P = .0003)., Conclusion: This meta-analysis has found some evidence showing that Ulinastatin reduces postoperative bleeding and RBC transfusion in patients undergoing cardiac surgery. However, these findings should be interpreted rigorously. Further well-conducted trials are required to assess the blood-saving effects and mechanisms of Ulinastatin.

Solar-driven water evaporation represents an environmentally benign method of water purification/desalination. However, the efficiency is limited by increased salt concentration and accumulation. Here, we propose an energy reutilizing strategy based on a bio-mimetic 3D structure. The spontaneously formed water film, with thickness inhomogeneity and temperature gradient, fully utilizes the input energy through Marangoni effect and results in localized salt crystallization. Solar-driven water evaporation rate of 2.63 kg m -2  h -1 , with energy efficiency of >96% under one sun illumination and under high salinity (25 wt% NaCl), and water collecting rate of 1.72 kg m -2  h -1 are achieved in purifying natural seawater in a closed system. The crystalized salt freely stands on the 3D evaporator and can be easily removed. Additionally, energy efficiency and water evaporation are not influenced by salt accumulation thanks to an expanded water film inside the salt, indicating the potential for sustainable and practical applications.

Background: Hemocoagulase is isolated and purified from snake venoms. Hemocoagulase agents have been widely used in the prevention and treatment of surgical bleeding. A systematic review was performed to evaluate the effects of hemocoagulase on postoperative bleeding and transfusion in patients who underwent cardiac surgery., Methods: Electronic databases were searched to identify all clinical trials comparing hemocoagulase with placebo/blank on postoperative bleeding and transfusion in patients undergoing cardiac surgery. Two authors independently extracted perioperative data and outcome data. For continuous variables, treatment effects were calculated as weighted mean difference and 95% confidential interval (CI). For dichotomous data, treatment effects were calculated as odds ratio and 95% CI. Each outcome was tested for heterogeneity, and randomized-effects or fixed-effects model was used in the presence or absence of significant heterogeneity. Sensitivity analyses were done by examining the influence of statistical model and individual trial on estimated treatment effects. Publication bias was explored through visual inspection of funnel plots of the outcomes. Statistical significance was defined as P < .05., Results: Our search yielded 12 studies including 900 patients, and 510 patients were allocated into hemocoagulase group and 390 into control group. Meta-analysis suggested that, hemocoagulase-treated patients had less bleeding volume, reduced red blood cells and fresh frozen plasma transfusion, and higher hemoglobin level than those of controlled patients postoperatively. Meta-analysis also showed that, hemocoagulase did not influence intraoperative heparin or protamine dosages and postoperative platelet counts. Meta-analysis demonstrated that, hemocoagulase-treated patients had significantly shorter postoperative prothrombin time, activated partial thromboplastin time, and thrombin time, higher fibrinogen level and similar D-dimer level when compared to control patients., Conclusion: This meta-analysis has found some evidence showing that hemocoagulase reduces postoperative bleeding, and blood transfusion requirement in patients undergoing cardiac surgery. However, these findings should be interpreted rigorously. Further well-conducted trials are required to assess the blood-saving effects and mechanisms of Hemocoagulase.

Pixelated color converters are envisioned to achieve full-color high-resolution display through down conversion of blue/ultraviolet(UV) micro-LEDs. Quantum dots (QDs) are promising narrow-band converters of high quantum efficiency and brightness enabling saturated colors with wide color gamut in displays. Here we demonstrate high-resolution pixelated red and green QDs/thiol-ene photo-polymer converters (single pixel down to 6 µm; converters array of 21 µm pixel, 30 µm pitch and sub 10 µm thickness) patterned through projection lithography. QDs capped with amine surface group are uniformly dispersed in thiol-ene photo-polymer matrix at high concentrations (up to 100 mg/mL), which reduces aggregation and improves conversion efficiency by 0.5-1 times compared to drop-cast QDs. Color cross-talk is also reduced through patterning light blocking walls between converter pixels.

Two-dimensional topological materials bearing time reversal-breaking magnetic fields support protected one-way edge modes. Normally, these edge modes adhere to physical edges where material properties change abruptly. However, even in homogeneous materials, topology still permits a unique form of edge modes - kink modes - residing at the domain boundaries of magnetic fields within the materials. This scenario, despite being predicted in theory, has rarely been demonstrated experimentally. Here, we report our observation of topologically-protected high-frequency kink modes - kink magnetoplasmons (KMPs) - in a GaAs/AlGaAs two-dimensional electron gas (2DEG) system. These KMPs arise at a domain boundary projected from an externally-patterned magnetic field onto a uniform 2DEG. They propagate unidirectionally along the boundary, protected by a difference of gap Chern numbers ([Formula: see text]) in the two domains. They exhibit large tunability under an applied magnetic field or gate voltage, and clear signatures of nonreciprocity even under weak-coupling to evanescent photons.

In wave physics and engineering, directional emission sets a fundamental limitation on conventional simple sources as their sizes should be sufficiently larger than their wavelength. Artificial metamaterial and animal biosonar both show potential in overcoming this limitation. Existing metamaterials arranged in periodic microstructures face great challenges in realizing complex and multiphase biosonar structures. Here, we proposed a physical directional emission model to bridge the gap between porpoises' biosonar and artificial metamaterial. Inspired by the anatomical and physical properties of the porpoise's biosonar transmission system, we fabricated a hybrid metamaterial system composed of multiple composite structures. We validated that the hybrid metamaterial significantly increased directivity and main lobe energy over a broad bandwidth both numerically and experimentally. The device displayed efficiency in detecting underwater target and suppressing false target jamming. The metamaterial-based physical model may be helpful to achieve the physical mechanisms of porpoise biosonar detection and has diverse applications in underwater acoustic sensing, ultrasound scanning, and medical ultrasonography., (© The Author(s) 2019. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

In September 2016, an invasive group A streptococcal disease outbreak occurred among residents of a residential aged care facility. An expert advisory group recommended mass prophylaxis for residents and staff in addition to strict infection control practices to prevent further spread. Whole genome sequencing confirmed the cases were related., (© Commonwealth of Australia CC BY-NC-ND)

The resolution of acoustic imaging suffers from diffraction limit due to the loss of evanescent field that carries subwavelength information. Most of the current methods for overcoming the diffraction limit in acoustics still operate in the near-field of the object. Here we demonstrate the design and experimental realization of an acoustic far-field subwavelength imaging system. Our system is based on wave vector filtering and conversion with a transmitter at the near-field and a spatially symmetrical receiver at the far-field. By tuning geometric parameters of the transmitting/receiving pair, different spatial frequency bands can be separated and projected to the far-field. Furthermore, far-field imaging and edge detection of subwavelength objects are experimentally demonstrated. The proposed system brings new possibilities for far-field subwavelength wave manipulation, which can be further applied to medical imaging, nondestructive testing, and acoustic communication.

Additive manufacturing based on liquid resin curing is one of the most promising methods to construct delicate structures. However, precision and speed are limited by the vertical adhesion of in situ cured resin at the curing interface. To overcome the unavoidable adhesion and to develop a general curing interface, we propose a slippery surface taking inspiration of the peristome surface of the pitcher plant. Such surface shows ultra-low adhesive energy at the curing interface due to the inhibition of the direct contact between the cured resin and the solid surface, which also increases the refilling speed of liquid resin. This ultra-low adhesive energy interface is effective for continuous 3D printing and provides insights into the physical mechanisms in reducing vertical solid-solid interfacial adhesion., Competing Interests: The authors declare no conflicts of interest.

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing challenge in the field is the fabrication of hybrid micro-nano structures using a facile, cost-effective, and high-throughput method. To overcome these challenges, this paper proposes a protocol to fabricate multiscale structures using only an imprint process with an anodic aluminum oxide (AAO) filter and an evaporative self-aggregation process of nanofibers. Unlike previous attempts that have aimed to straighten nanofibers, we demonstrate a unique fabrication method for multiscale aggregated nanofibers with high aspect ratios. Furthermore, the surface morphology and wettability of these structures on various liquids were investigated to facilitate their use in multifunctional surfaces.

Kirigami enables versatile shape transformation from two-dimensional (2D) precursors to 3D architectures with simplified fabrication complexity and unconventional structural geometries. We demonstrate a one-step and on-site nano-kirigami method that avoids the prescribed multistep procedures in traditional mesoscopic kirigami or origami techniques. The nano-kirigami is readily implemented by in situ cutting and buckling a suspended gold film with programmed ion beam irradiation. By using the topography-guided stress equilibrium, rich 3D shape transformation such as buckling, rotation, and twisting of nanostructures is precisely achieved, which can be predicted by our mechanical modeling. Benefiting from the nanoscale 3D twisting features, giant optical chirality is achieved in an intuitively designed 3D pinwheel-like structure, in strong contrast to the achiral 2D precursor without nano-kirigami. The demonstrated nano-kirigami, as well as the exotic 3D nanostructures, could be adopted in broad nanofabrication platforms and could open up new possibilities for the exploration of functional micro-/nanophotonic and mechanical devices.

Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light-emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin-film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC-TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain-bandwidth product, and a 100-photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness-optimized SC-TF with much higher mobility and longer recombination time. The results indicate that high-performance perovskite devices based on SC-TF may become competitive in modern optoelectronics., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Myelination is critical for transduction of neuronal signals, neuron survival and normal function of the nervous system. Myelin disorders account for many debilitating neurological diseases such as multiple sclerosis and leukodystrophies. The lack of experimental models and tools to observe and manipulate this process in vitro has constrained progress in understanding and promoting myelination, and ultimately developing effective remyelination therapies. To address this problem, we developed synthetic mimics of neuronal axons, representing key geometric, mechanical, and surface chemistry components of biological axons. These artificial axons exhibit low mechanical stiffness approaching that of a human axon, over unsupported spans that facilitate engagement and wrapping by glial cells, to enable study of myelination in environments reflecting mechanical cues that neurons present in vivo. Our 3D printing approach provides the capacity to vary independently the complex features of the artificial axons that can reflect specific states of development, disease, or injury. Here, we demonstrate that oligodendrocytes' production and wrapping of myelin depend on artificial axon stiffness, diameter, and ligand coating. This biofidelic platform provides direct visualization and quantification of myelin formation and myelinating cells' response to both physical cues and pharmacological agents.

Two limitations of additive manufacturing methods that arise from layer-based fabrication are slow speed and geometric constraints (which include poor surface quality). Both limitations are overcome in the work reported here, introducing a new volumetric additive fabrication paradigm that produces photopolymer structures with complex nonperiodic three-dimensional geometries on a time scale of seconds. We implement this approach using holographic patterning of light fields, demonstrate the fabrication of a variety of structures, and study the properties of the light patterns and photosensitive resins required for this fabrication approach. The results indicate that low-absorbing resins containing ~0.1% photoinitiator, illuminated at modest powers (~10 to 100 mW), may be successfully used to build full structures in ~1 to 10 s.

Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the conventional (single or colloidal) dye molecules and quantum dots. In this paper, we verify that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at a picosecond timescale. Our streak-camera lifetime measurement and interacting lattice-dipole calculation reveal that the metal-mediated dipole-dipole interaction shortens the fluorescent lifetime to about one-half and increases the energy dissipation rate by 10 times that expected from the noninteracting single-dipole picture. Our finding can enrich our understanding of nanoscale energy transfer in molecular excitonic systems and may designate a unique direction for developing fast and efficient optoelectronic devices., Competing Interests: The authors declare no conflict of interest.

We propose a two-dimensional plasmonic platform-periodically patterned monolayer graphene-which hosts topological one-way edge states operable up to infrared frequencies. We classify the band topology of this plasmonic system under time-reversal-symmetry breaking induced by a static magnetic field. At finite doping, the system supports topologically nontrivial band gaps with mid-gap frequencies up to tens of terahertz. By the bulk-edge correspondence, these band gaps host topologically protected one-way edge plasmons, which are immune to backscattering from structural defects and subject only to intrinsic material and radiation loss. Our findings reveal a promising approach to engineer topologically robust chiral plasmonic devices and demonstrate a realistic example of high-frequency topological edge states.

Monolayer MoS 2 is an emerging two-dimensional semiconductor that has seen wide applications in optoelectronic and light-emitting devices. Here we report on the antenna-enhanced spontaneous emission of monolayer MoS 2 , which has weak absorbance and low intrinsic quantum yield. The ultrathin silver platelet antennas we use can both increase the absorption cross-section and improve the transmission efficiency via controlling the optical field at nanometer scale. Experimental results indicate the photoluminescence enhancement can reach 4 times, which is also supported by numerical analysis of both excitation and emission processes with respect to the thickness of spacer layer. This ultrathin structure can facilitate the development of on-chip emitters and valley-based devices, especially in cases of large area sample or flexible substrate.