All-van-der-Waals Heterostructure of MoS Grating and InSe Flake for Spectrally Selective Polarization-Sensitive Photodetection in NIR Region.

Near-infrared (NIR) polarization photodetectors based on 2D materials hold immense potential for numerous optoelectronic applications. To enhance the weak light-matter interaction in 2D materials, integrating 2D semiconductors with metallic plasmonic nanostructures presents an effective solution. However, such metallic plasmonic nanostructures suffer from high optical loss in the infrared region owing to inherent Ohmic losses in metals.

Superior Visible Photoelectric Response with Au/CuNiSnS Core-Shell Nanocrystals.

The incorporation of plasmonic metal nanostructures into semiconducting chalcogenides in the form of core-shell structures provides a promising approach to enhancing the performance of photodetectors. In this study, we combined Au nanoparticles with newly developed copper-based chalcogenides CuNiSnS (Au/CNTS) to achieve an ultrahigh optoelectronic response in the visible regime. The high-quality Au/CNTS core-shell nanocrystals (NCs) were synthesized by developing a unique colloidal hot-injection method, which allowed for excellent control over sizes, shapes, and elemental compositions.

Terahertz Combined with Metamaterial Microfluidic Chip for Troponin Antigen Detection.

In this paper, we use terahertz combined with metamaterial technology as a powerful tool to identify analytes at different concentrations. Combined with the microfluidic chip, the experimental measurement can be performed with a small amount of analyte. In detecting the troponin antigen, surface modification is carried out by biochemical binding.

Hotspots in action: near-infrared light mediated photoelectrochemical oxygen evolution on high index faceted plasmonic gold nanoarchitectures.

Photo-induced electrochemical water splitting is a fascinating approach to overcome the present energy demands as well as environmental issues. To this end, near-infrared (NIR) photocatalysts stand out as promising candidates (where 53% of the solar light is NIR light) to solve the present energy crisis but the lack of NIR-activated photocatalysts has remained a great challenge for decades. Herein, for the first time, we report the synthesis of high-index faceted plasmonic Au nano-branched 12 tip nanostars, which can absorb the whole spectral region of electromagnetic radiation (UV-vis-NIR), for efficient water splitting.

Self-Assembly Anchored Cationic Copolymer Interfaces for Applying the Control of Counterion-Induced Bacteria Killing/Release Procedure.

In recent years, daily hygiene and disease control issues have received increasing attention, especially the raging epidemics caused by the spread of deadly viruses. The construction of the interface of new polymer materials is focused on, which can provide a cyclic operation process for the killing and releasing of bacteria, and perform repeated regeneration, which is of great significance for the development of advanced medical biomaterials. In order to explore the basic physical phenomena of bacterial attachment and detachment on the polymer material interface by different amine groups, this study plans to synthesize four different butyl methacrylate (BMA)-based cationic copolymers with primary, ternary, and quaternary amine groups, and compare their effects on bactericidal efficiency.

Sensitivity Enhancement and Probiotic Detection of Microfluidic Chips Based on Terahertz Radiation Combined with Metamaterial Technology.

Terahertz (THz) radiation has attracted wide attention in recent years due to its non-destructive properties and ability to sense molecular structures. In applications combining terahertz radiation with metamaterial technology, the interaction between the terahertz radiation and the metamaterials causes resonance reactions; different analytes have different resonance performances in the frequency domain. In addition, a microfluidic system is able to provide low volume reagents for detection, reduce noise from the environment, and concentrate the sample on the detection area.

Demonstration of a Superior Deep-UV Surface-Enhanced Resonance Raman Scattering (SERRS) Substrate and Single-Base Mutation Detection in Oligonucleotides.

In life science, rapid mutation detection in oligonucleotides is in a great demand for genomic and medical screening. To satisfy this demand, surface-enhanced resonance Raman spectroscopy (SERRS) in the deep-UV (DUV) regime offers a promising solution due to its merits of label-free nature, strong electromagnetic confinement, and charge transfer effect. Here, we demonstrate an epitaxial aluminum (Al) DUV-SERRS substrate that resonates effectively with the incident Raman laser and the ss-DNA at 266 nm, yielding significant SERRS signals of the detected analytes.

Achieving broad absorption band and high incident angles by stochastically-distributed oblique-flat-sheet metamaterial perfect absorbers.

In this work, we integrated a periodic seed layer and oblique deposition method to fabricate a stochastically-distributed oblique-flat-sheet metamaterial perfect absorber (MPA). Such design could increase its absorption bandwidth and tolerance to high angle-incidence due to the fact that various oblique flat sheets offer different resonance conditions while even a single oblique flat sheet could provide different optical paths for resonance. On the other hand, a seed layer could reduce uncertainty regarding to direct oblique deposition and provide abilities to manipulate the bandwidth of the MPA.

Convergent charge interval spacing of zwitterionic 4-vinylpyridine carboxybetaine structures for superior blood-inert regulation in amphiphilic phases.

Antifouling materials are indispensable in the biomedical field, but their high hydrophilicity and surface free energy provoke contamination on surfaces under atmospheric conditions, thus limiting their applicability in medical devices. This study proposes a new zwitterionic structure, 4-vinylpyridine carboxybetaine (4VPCB), that results in lower surface free energy and increases biological inertness. In the design of 4VPCB, one to three carbon atoms are inserted between the positive charge and negative charge (carbon space length, CSL) of the pyridyl-containing side chain to adjust hydration with water molecules.

Gate-Tunable Plasmon-Enhanced Photodetection in a Monolayer MoS Phototransistor with Ultrahigh Photoresponsivity.

Monolayer transition metal dichalcogenides (TMDs), direct bandgap materials with an atomically thin nature, are promising materials for electronics and photonics, especially at highly scaled lateral dimensions. However, the characteristically low total absorption of photons in the monolayer TMD has become a challenge in the access to and realization of monolayer TMD-based high-performance optoelectronic functionalities and devices. Here, we demonstrate gate-tunable plasmonic phototransistors (photoFETs) that consist of monolayer molybdenum disulfide (MoS) photoFETs integrated with the two-dimensional plasmonic crystals.

Ultra-broadband, lithography-free, omnidirectional, and polarization-insensitive perfect absorber.

Perfect absorbers (PAs) at near infrared allow various applications such as biosensors, nonlinear optics, color filters, thermal emitters and so on. These PAs, enabled by plasmonic resonance, are typically powerful and compact, but confront inherent challenges of narrow bandwidth, polarization dependence, and limited incident angles as well as requires using expensive lithographic process, which limit their practical applications and mass production. In this work, we demonstrate a non-resonant PA that is comprised of six continuous layers of magnesium fluoride (MgF) and chromium (Cr) in turns.

Perovskite Quantum Dot Lasing in a Gap-Plasmon Nanocavity with Ultralow Threshold.

Lead halide perovskite materials have recently received considerable attention for achieving an economic and tunable laser owing to their solution-processable feature and promising optical properties. However, most reported perovskite-based lasers operate with a large lasing-mode volume, resulting in a high lasing threshold due to the inefficient coupling between the optical gain medium and cavity. Here, we demonstrate a continuous-wave nanolasing from a single lead halide perovskite (CsPbBr) quantum dot (PQD) in a plasmonic gap-mode nanocavity with an ultralow threshold of 1.

Epitaxial Aluminum Surface-Enhanced Raman Spectroscopy Substrates for Large-Scale 2D Material Characterization.

Surface-enhanced Raman spectroscopy (SERS) is an ultrasensitive technique to identify vibrational fingerprints of trace analytes. However, present SERS techniques suffer from the lack of uniform, reproducible, and stable substrates to control the plasmonic hotspots in a wide spectral range. Here, we report the promising application of epitaxial aluminum films as a scalable plasmonic platform for SERS applications.

Achieving sub-wavelength imaging through a flat hyperlens in a modified anodic aluminum oxide template.

Constrained by the diffraction limit, a lens can only resolve features larger than half of the incident wavelength owing to the decaying nature of evanescent waves. Several novel devices have been proposed, for example, superlenses and hyperlenses to break this limit. In this work, we present a flat hyperlens composed of silver nanowires embedded in a modified anodic aluminum oxide (AAO) template to demonstrate subwavelength imaging.

Application of a Terahertz System Combined with an X-Shaped Metamaterial Microfluidic Cartridge.

Terahertz (THz) radiation has attracted wide attention for its ability to sense molecular structure and chemical matter because of a label-free molecular fingerprint and nondestructive properties. When it comes to molecular recognition with terahertz radiation, our attention goes first towards the absorption spectrum, which is beyond the far infrared region. To enhance the sensitivity for similar species, however, it is necessary to apply an artificially designed metamaterial sensor for detection, which confines an electromagnetic field in an extremely sub-wavelength space and hence receives an electromagnetic response through resonance.

Ultrasensitive and Selective Gas Sensor Based on a Channel Plasmonic Structure with an Enormous Hot Spot Region.

We present experimental and theoretical studies of a metamaterial-based plasmonic structure to build a plasmonic-molecular coupling detection system. High molecular sensitivity is realized only when molecules are located in the vicinity of the enhanced field (hot spot region); thus, introducing target molecules in the hot spot region to maximize plasmonic-molecular coupling is crucial to developing the sensing technology. We design a metamaterial consisting of a vertically oriented metal insulator metal (MIM) structure with a 25 nm channel sandwiched between two metal films, which enables the delivery of molecules into the large ravinelike hot spot region, offering an ultrasensitive platform for molecular sensing.

Disease antigens detection by silicon nanowires with the efficiency optimization of their antibodies on a chip.

Enhancing the efficiency of antibody protein immobilized on a silicon nanowire-based chip for their antigens detection is reported. An external electric field (EEF) is applied to direct the orientation of antibodies during their immobilization on a chip. Atomic force microscopy (AFM) is used to measure the binding forces between immobilized antibody and targeting antigen under the influence of EEF at different angles.

Porous aluminum electrodes with 3D channels and zig-zag edges for efficient hydrogen evolution.

An eco-friendly electrochemical approach, including base and acid treatments, and anodization, has been developed for preparation of defect-rich porous aluminum electrodes for efficient hydrogen evolution. A small Tafel slope value of 43 mV dec-1 reveals improved reaction kinetics through the micropores, 3D channels, and zig-zag edges of the aluminum electrode. It exhibits an onset potential of 460 mV and an overpotential of 580 mV at the current density of 10 mA cm-2 due to the porous and edge structures that enhance the charge transfer and mass transport.

Experimental demonstration of broadband light trapping by exciting surface modes of an all-dielectric taper.

We design an all-dielectric taper and then excite its surface modes by illuminating a plane wave upon the taper to achieve broadband light trapping spanning from 20 to 100 GHz. Via Lewin's theory, such excitation of surface modes could be analogous to "trapped rainbow", i.e.