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Rapid and sensitive detection of volatile organic compounds (VOCs) is essential for environmental monitoring and disease diagnosis. Surface-enhanced Raman scattering (SERS) has a natural analyte recognition ability and can realize ultra-sensitive detection. Herein, we report a plasmonic nose based on a 3D-microneedle array coated with Ag nanoparticles for fast and ultrasensitive SERS detection of VOCs vapor. Since the surface of the 8.3 μm high microneedle is completely covered by 'hot spots', which can effectively slow down the diffusion of gas molecules, so as to ensure that the gas molecules are in full contact with 'hot spots', and then detected by the plasmonic nose. Experiments for gaseous 4-methylbenzenethiol detection with a fast responding time (as short as 1 s) are realized, and gaseous 4-ethylbenzaldehyde as a lung cancer marker is also captured with a 10 ppb limit of detection. The results demonstrate that the plasmonic nose is of great potential for environmental monitoring and disease diagnosis. [ABSTRACT FROM AUTHOR]

A novel broadband solar absorber is numerically studied based on the commercial digital versatile disc (DVD). Refractory titanium (Ti) material is artificially coated onto the surface of the DVD, which then forms the plasmonic resonant metasurface. Spectral average absorption reaches 91.3% in the whole visible and near-infrared range (0.38–1.50 μm). The total solar absorption in these energy regions is also up to 92.1%. Moreover, the high spectral absorption is insensitive to the incident angle. Interestingly, the absorption is observed to be with high tolerance for the polarized light even if the grating structure is used in the platform. These features suggest that the broadband solar absorption can be maintained well under complex electromagnetic surroundings. Otherwise, the absorbed energy is mainly confined at the proximity surface area of the Ti cavity, which suggests the strong plasmonic near-field localization and paves the feasible way to carry out the local heating operation for thermal antibacterial/antivirus applications. [ABSTRACT FROM AUTHOR]

Metamaterials (MMs) offer great potential for achieving optical absorption due to their novel electromagnetic properties. MM absorbers can overcome the thickness limitation and provide excellent absorption performance over the wide frequency range, thereby enable the swift emergence of some promising applications. Moreover, the optical sensors based on MM absorbers have shown great potential in several fields. This review concentrates on the recent progresses in MM-based optical absorbers and spectral sensing. We present four aspects of MM-based optical absorption: the metal-insulation-metal arrangements, the optical coherence, the functional materials, and some novel approaches. Also, we present three aspects of MM-based optical sensing: the refractive index sensing, gas and molecule sensing, and surface-enhanced Raman scattering. Finally, the current challenges and prospects in device designs, fabrications have been discussed. This review is with the purpose to give a generalized knowledge of MMs for optical absorption and sensing, thus inspiring the investigations on MMs for other devices and their practical applications. [ABSTRACT FROM AUTHOR]

Refractory materials have wide applications due to their high thermal and chemical stability. In this work, we numerically design the plasmonic structure for perfect light absorption using the resonant behaviours for these materials. The results of the simulation are presented using the three-dimensional finite-difference time-domain method. The maximum absorption reaches 99.9% and the near-unity absorption window spans a bandwidth of 1182 nm from 413 nm in the visible to 1595 nm in the near-infrared range. Strong plasmonic near-field coupling between the adjacent parts in the split circular Ti resonator and their coupling to the plasmon resonances of the TiN layer are the main reasons for the ultra-broadband perfect absorption. Moreover, the absorption is observed to be incident angle insensitive and polarization independent. Absorption properties can be manipulated via tuning the structural parameters. These impressive absorption features and the high thermal stability can have wide applications in the high-intensity or extreme condition operation such as laser pumping and nonlinear optics, and solar related technologies including thermal steam generation and desalination of seawater. [ABSTRACT FROM AUTHOR]