Abstract
Topological photonics provides a fundamental framework for robust manipulation of light, including directional transport and localization with built-in immunity to disorder. Combined with an ...optical gain, active topological cavities hold special promise for a design of light-emitting devices. Most studies to date have focused on lasing at topological edges of finite systems or domain walls. Recently discovered higher-order topological phases enable strong high-quality confinement of light at the corners. Here, we demonstrate lasing action of corner states in nanophotonic topological structures. We identify several multipole corner modes with distinct emission profiles via hyperspectral imaging and discern signatures of non-Hermitian radiative coupling of leaky topological states. In addition, depending on the pump position in a large-size cavity, we generate selectively lasing from either edge or corner states within the topological bandgap. Our studies provide the direct observation of multipolar lasing and engineered collective resonances in active topological nanostructures.
Abstract
Wavelength-scale lasers provide promising applications through low power consumption requiring for optical cavities with increased quality factors. Cavity radiative losses can be suppressed ...strongly in the regime of optical bound states in the continuum; however, a finite size of the resonator limits the performance of bound states in the continuum as cavity modes for active nanophotonic devices. Here, we employ the concept of a supercavity mode created by merging symmetry-protected and accidental bound states in the continuum in the momentum space, and realize an efficient laser based on a finite-size cavity with a small footprint. We trace the evolution of lasing properties before and after the merging point by varying the lattice spacing, and we reveal this laser demonstrates the significantly reduced threshold, substantially increased quality factor, and shrunken far-field images. Our results provide a route for nanolasers with reduced out-of-plane losses in finite-size active nanodevices and improved lasing characteristics.
The coronavirus disease 2019 (COVID-19) pandemic has been a major public health challenge in 2020. Early diagnosis of COVID-19 is the most effective method to control disease spread and prevent ...further mortality. As such, a high-precision and rapid yet economic assay method is urgently required. Herein, we propose an innovative method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using isothermal amplification of nucleic acids on a mesh containing multiple microfluidic pores. Hybridization of pathogen DNA and immobilized probes forms a DNA hydrogel by rolling circle amplification and, consequently, blocks the pores to prevent fluid movement, as observed. Following optimization of several factors, including pore size, mesh location, and precision microfluidics, the limit of detection (LOD) for SARS-CoV-2 was determined to be 0.7 aM at 15-min incubation. These results indicate rapid, easy, and effective detection with a moderate-sized LOD of the target pathogen by remote point-of-care testing and without the requirement of any sophisticated device.
•Rapid DNA gelation formed with modified RCA using a dumbbell-shaped template.•The smaller pores of nylon mesh, the quicker the blockage can occur.•Significant enhancement in detection of clogging pores with precision microfluidics.•The LOD of SARS-CoV-2 was 0.7 aM within 15 min incubation, equivalent to conventional PCR performance.
Harvesting energy from natural resources is of significant interest because of their abundance and sustainability. Seawater is the most abundant natural resource on earth, covering two‐thirds of the ...surface. The rechargeable seawater battery is a new energy storage platform that enables interconversion of electrical energy and chemical energy by tapping into seawater as an infinite medium. Here, an overview of the research and development activities of seawater batteries toward practical applications is presented. Seawater batteries consist of anode and cathode compartments that are separated by a Na‐ion conducting membrane, which allows only Na+ ion transport between the two electrodes. The roles and drawbacks of the three key components, as well as the development concept and operation principles of the batteries on the basis of previous reports are covered. Moreover, the prototype manufacturing lines for mass production and automation, and potential applications, particularly in marine environments are introduced. Highlighting the importance of engineering the cell components, as well as optimizing the system level for a particular application and thereby successful market entry, the key issues to be resolved are discussed, so that the seawater battery can emerge as a promising alternative to existing rechargeable batteries.
Rechargeable seawater batteries tap into earth‐abundant natural seawater as the active material to transform between electrical energy and chemical energy. The progress, challenges, and prospects of seawater batteries for practical applications are summarized.
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•Pyrogallol conjugation of chitosan on primary amine increase the solubility at physiological pH.•Pyrogallol tailored chitosan exhibits improved wet adhesion than commercially ...available tissue sealant -fibrin glue.•Chitosan-gallic acid hydrogel can be used for microfiber fabrication via electrospinning to mimic natural structure.•Pyrogallol functionalization improved hemostasis function than parent chitosan.
The nature-inspired fabrication of tissue adhesive and hemostatic hydrogels holds great potential for restoring damaged internal tissue in regenerative medicine. However, feeble adhesion, multifaceted systems, prohibitive costs, and toxicity impede their applications in the medical field. In order to solve this problem, we fabricated chitosan-based wet tissue adhesive with hemostatic functions inspired by the self-healing mechanism of the tunicate. In order to introduce pyrogallol moiety, gallic acids, which are broadly distributed in nature, were incorporated into chitosan backbone, a key residue for the self-healing process of tunichrome in tunicates. The in vitro adhesion test results of the tunicate-inspired hydrogel exhibited two-fold greater adhesion ability in wet condition than did fibrin glue, a commercially available surgical glue. Further, the tunicate-inspired hydrogel exhibited significantly more platelet adhesion and blood clotting ability than the parent polymer. We also demonstrated the ability of the derivative to completely mimic the tunicate’s fibrous structure by fabricating an electrospun mat. The hemostatic function vis-à-vis the wet adhesiveness of the synthesized chitosan-based material may be useful for facilitating the shortcomings of the restorative tissue medicine. Additionally, the electrospinning capability will enable the modulate of the structure-property relationship and a three-dimensional design for its application site.
Face masks are used to protect the wearer from harmful external air and to prevent transmission of viruses from air exhaled by potentially infected wearers to the surrounding people. In this study, ...we examined the potential utility of masks for collecting viruses contained in exhaled breath and detected the collected viruses via various molecular tests. Using KF94 masks, the inner electrostatic filter was selected for virus collection, and an RNA extraction protocol was developed for the face mask. Virus detection in worn mask samples was performed using PCR and rolling circle amplification (RCA) tests and four different target genes (N, E, RdRp, and ORF1ab genes). The present study confirmed that the mask sample tests showed positive SARS-CoV-2 results, similar to the PCR tests using nasopharyngeal swab samples. In addition, the quantity of nucleic acid collected in the masks linearly increased with wearing time. These results suggest that samples for SARS-CoV-2 tests can be collected in a noninvasive, quick, and easy method by simply submitting worn masks from subjects, which can significantly reduce the hassle of waiting at airports or public places and concerns about cross-infection. In addition, it is expected that miniaturization technology will integrate PCR assays on face masks in the near future, and mask-based self-diagnosis would play a significant role in resolving the pandemic situation.
The fundamental challenge in designing transparent pressure sensors is the ideal combination of high optical transparency and high pressure sensitivity. Satisfying these competing demands is commonly ...achieved by a compromise between the transparency and usage of a patterned dielectric surface, which increases pressure sensitivity, but decreases transparency. Herein, a design strategy for fabricating high‐transparency and high‐sensitivity capacitive pressure sensors is proposed, which relies on the multiple states of nanoparticle dispersity resulting in enhanced surface roughness and light transmittance. We utilize two nanoparticle dispersion states on a surface: (i) homogeneous dispersion, where each nanoparticle (≈500 nm) with a size comparable to the visible light wavelength has low light scattering; and (ii) heterogeneous dispersion, where aggregated nanoparticles form a micrometer‐sized feature, increasing pressure sensitivity. This approach is experimentally verified using a nanoparticle‐dispersed polymer composite, which has high pressure sensitivity (1.0 kPa–1), and demonstrates excellent transparency (>95%). We demonstrate that the integration of nanoparticle‐dispersed capacitor elements into an array readily yields a real‐time pressure monitoring application and a fully functional touch device capable of acting as a pressure sensor‐based input device, thereby opening up new avenues to establish processing techniques that are effective on the nanoscale yet applicable to macroscopic processing.
A design strategy for fabricating high‐transparency and high‐sensitivity capacitive pressure sensors is proposed, which relies on the multiple states of nanoparticle dispersity resulting in enhanced surface roughness and light transmittance. This approach is experimentally verified using a nanoparticle‐dispersed polymer composite, which, despite its low dielectric constant (≈3.0), has high pressure sensitivity (1.0 kPa−1) and demonstrates excellent transparency (>95%).
Abstract
The study of topological phases of light underpins a promising paradigm for engineering disorder-immune compact photonic devices with unusual properties. Combined with an optical gain, ...topological photonic structures provide a novel platform for micro- and nanoscale lasers, which could benefit from nontrivial band topology and spatially localized gap states. Here, we propose and demonstrate experimentally active nanophotonic topological cavities incorporating III–V semiconductor quantum wells as a gain medium in the structure. We observe room-temperature lasing with a narrow spectrum, high coherence, and threshold behaviour. The emitted beam hosts a singularity encoded by a triade cavity mode that resides in the bandgap of two interfaced valley-Hall periodic photonic lattices with opposite parity breaking. Our findings make a step towards topologically controlled ultrasmall light sources with nontrivial radiation characteristics.
Responsive photonic crystals (PCs) have attracted much attention due to their broad applications in the field of chemical and physical sensing through varying optical properties when exposed to ...external stimuli. In particular, assembly of block copolymers (BCPs) has proven to be a robust platform for constructing PCs in the form of films or bulk. Here, the generation of BCPs photonic microspheres is presented with 3D periodical concentric lamellar structures through confined self‐assembly. The structural color of the spherical PCs can be tuned by selective swelling of one block, yielding large change of optical property through varying both layer thickness and refraction index of the domains. The as‐formed spherical PCs demonstrate large reflection wavelength shift (≈400–700 nm) under organic solvent permeation and pH adjustment. Spherical shape and structural symmetry endow the formed spherical PCs with rotation independence and monochrome, which is potentially useful in the fields of displays, sensing, and diagnostics.
Block copolymer photonic microspheres with onion‐like structure are generated via confined assembly. The structural color of the responsive photonic crystals (PCs) can be tuned by selective swelling, yielding large optical tunability by varying layer thickness and refraction index of the domains. The formed spherical PCs demonstrate a large reflection wavelength shift under solvent permeation and pH adjustment, as well as rotation independence. They are potentially useful in displays, sensing, and diagnostics.
Mussel‐inspired self‐polymerized catecholamine coatings have been widely utilized as a versatile coating strategy that can be applied to a variety of substrates. For the first time, nanomechanical ...measurements and an evaluation of the contribution of primary amine groups to poly(catecholamine) coatings have been conducted using a surface‐forces apparatus. The adhesive strength between the poly(catecholamine) layers is 30‐times higher than that of a poly(catechol) coating. The origin of the strong attraction between the poly(catecholamine) layers is probably due to surface salt displacement by the primary amine, π–π stacking (the quadrupole–quadrupole interaction of indolic crosslinks), and cation–π interactions (the monopole–quadrupole interaction between positively charged amine groups and the indolic crosslinks). The contribution of the primary amine group to the catecholamine coating is vital for the design and development of mussel‐inspired catechol‐based coating materials.
Give it some stick: The adhesive strength of self‐polymerized catecholic coating layers was measured with a surface forces apparatus. The adhesive strength between poly(catecholamine) layers is 30‐times higher than that between poly(catechol) layers. The origin of the strong attraction between poly(catecholamine) layers is possibly due to surface salt displacement, π–π stacking, and cation–π interactions involving the primary amine moiety.
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