Cicada Wing Inspired Template-Stripped SERS Active 3D Metallic Nanostructures for the Detection of Toxic Substances

Abstract

This article introduces a bioinspired, cicada wing-like surface-enhanced Raman scattering (SERS) substrate based on template-stripped crossed surface relief grating (TS-CSRG). The substrate is polarization-independent, has tunable nanofeatures and can be fabricated in a cleanroom-free environment via holographic exposure followed by template-stripping using a UV-curable resin. The bioinspired nanostructures in the substrate are strategically designed to minimize the reflection of light for wavelengths shorter than their periodicity, promoting enhanced plasmonic regions for the Raman excitation wavelength at 632.8 nm over a large area. The grating pitch that enables an effective SERS signal is studied using Rhodamine 6G, with enhancement factors of the order of 1 × 104. Water contact angle measurements reveal that the TS-CSRGs are equally hydrophobic to cicada wings, providing them with potential self-cleaning and bactericidal properties. Finite-difference time-domain simulations are used to validate the nanofabrication parameters and to further confirm the polarization-independent electromagnetic field enhancement of the nanostructures. As a real-world application, label-free detection of melamine up to 1 ppm, the maximum concentration of the contaminant in food permitted by the World Health Organization, is demonstrated. The new bioinspired functional TS-CSRG SERS substrate holds great potential as a large-area, label-free SERS-active substrate for medical and biochemical sensing applications.

Bionic Plasmonic Nanoarrays Excited by Radially Polarized Vector Beam for Metal-Enhanced Fluorescence

“…It is because there exists nanoarrays on the surface of the wings [ 45 ]. Cicada wings have been used for fabrication of SERS substrate [ 46 , 47 ]. It is promising to use the wings as templates to replicate and realize the low-cost nano-fabrication by nanoimprint process.…”

Surface-Enhanced Raman Scattering on Silver Sinusoidal Nanograting: Impact of Interactions of Grating-Coupled Surface Plasmon Polaritons

“…The medium above the Ag layer is H2O, which functions as a concentrator, effectively increasing the volumetric density of trace molecules. Fabrication of the sinusoidal nanograting can be performed using the rapid and high-throughput interferometric technique described elsewhere [1,25] . The Ag sinusoidal nanograting, to provide the metallic interface for the SPP excitation, has a large-area approach for target analyte detection, in contrast to established hot spot methods [25] .…”

Fabrication of optical hydrophobic metasurfaces resembling the surface structure of Peruvian lily flower petals

“…As an example, certain flowers lure bees by reflecting certain blue or UV wavelengths of light which are more attractive for pollinators [10]. Another example of superficial nanostructures was observed on cicada wings which exhibit antireflective properties and make them invisible to their predators [11]. In addition to the optical responses that they exhibit, plants use the micro or nanostructures on their epidermal surfaces as a physiological tool to absorb or repel water [12].…”