Flexible PDMS-Based SERS Substrates Replicated from Beetle Wings for Water Pollutant Detection

Abstract

The flexible surface-enhanced Raman scattering (SERS) sensor, which has the bionic 3D nanoarray structure of a beetle-wing substrate (BWS), was successfully prepared by replicated technology and thermal evaporation. The bionic structure was replicated with polydimethylsiloxane (PDMS) and then silver (Ag) nanoisland thin films were deposited by thermal evaporation. The deposition times and thicknesses (25–40 nm) of the Ag thin films were manipulated to find the optimal SERS detection capability. The Ag nanoisland arrays on the surface of the bionic replicated PDMS were observed by scanning electron microscope (SEM), X-ray diffraction (XRD), and contact angle, which can generate strong and reproducible three-dimensional hotspots (3D hotspots) to enhance Raman signals. The water pollutant, rhodamine 6G (R6G), was used as a model molecule for SERS detection. The results show that 35 nm Ag deposited on a PDMS-BWS SERS substrate displays the strongest SERS intensity, which is 10 times higher than that of the pristine BWS with 35 nm Ag coating, due to the excellent 3D bionic structure. Our results demonstrate that bionic 3D SERS sensors have the potential to be applied in wearable devices and sensors to detect biomolecules and environmental pollutants, such as industrial wastewater, in the future.

Magnetic Properties of Amorphous Ta/CoFeB/MgO/Ta Thin Films on Deformable Substrates with Magnetic Field Angle and Tensile Strain

“…Regarding the PEN substrate, peaks were observed at approximately 27° and 56° [36]. Peaks corresponding to the PDMS and PI substrates were observed at 11° [37] and 21° [38], respectively. Other peaks, such as those of Ta, CoFeB, and MgO, were not observed, except for those of the substrates.…”

“…Additionally, variations in M r /M s imply that multi-grains or magnetic domains are composed of magnetic anisotropies of various orientations [43,44]. These values (H c and M r /M s ) can be used to qualitatively evaluate the magnetic anisotropy of a sample [38,45,46].…”

Design, Fabrication, and Applications of SERS Substrates for Food Safety Detection: Review

“…To further simplify the fabrication of the SERS substrate, some biological or commercial substrates were applied to be a simple SERS substrate, such as a cuttlebone-derived organic matrix [ 98 ], diatomite [ 138 ], beetle wings [ 139 ], cotton swabs [ 140 , 141 ], and filter paper [ 142 ]. The biological materials usually have complex structures such as the “wall-septa” on the cuttlebone [ 98 ], 3D periodic microstructures on the beetle wings, and the micro porous structure on the diatomite are naturally formed micro-to-nano structures that can be directly decorated with MNPs [ 98 , 139 ] or that used to be the mold to translate the nanostructure to PDMS [ 139 ]. Other simple SERS substrate supporters are commercial substrates such as cotton swabs [ 140 , 141 ] and filter paper [ 142 ].…”

Curvature-Insensitive Transparent Surface-Enhanced Raman Scattering Substrate Based on Large-Area Ag Nanoparticle-Coated Wrinkled Polystyrene/Polydimethylsiloxane Film for Reliable In Situ Detection

“…This approach increases the number of hot spots and capture sites while conforming more closely to complex surfaces [ 26 ]. However, current methods for creating these structures, such as molding and oxygen plasma treatment, are not suitable for the high-throughput production of SERS substrates in a simple and cost-effective manner [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Therefore, there is an urgent demand for a simple, efficient, and affordable technology that can create structured 3D features on large-scale PDMS films.…”