Electrochemically up-regulated surface-enhanced Raman spectroscopy (E-SERS) effectively increases Raman signal intensities. However, the instrumental requirements and the conventional measurement conditions in an electrolyte cell have hampered its application in fast and on-site detection. To circumvent the inconveniences of E-SERS, we propose a self-energizing substrate that provides electrical potential by converting film deformation from a finger press into stored electrical energy. The substrate combines an energy conversion film and a SERS-active Ag nanowire layer. A composite film prepared from a piezoelectric polymer matrix and surface-engineered rGO that simultaneously presents high permittivity and low dielectric loss is the key component herein. Using our substrate, increased E-SERS signals up to 10 times from a variety of molecules were obtained in the open air. Various tests on real-life sample surfaces demonstrated the potentials of the substrate in fast on-site detection.
This study reports on a self-powered mechanoluminescent flexible film that converts human movement into green, yellow, and white light that are visible to the naked eye. The film is simply a highly porous composite material that was prepared using a piezoelectric polymer and ZnS luminescent powders. The highly effective mechanoluminescence capabilities stem from both the film's porous structure and the strong interactions between poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ZnS particles. The porous film's sensitivity helps the conversion of mechanical disturbances into electrical energies and induces the electroluminescence of ZnS particles. The particle-film interactions induced a high β-phase, which is the most effective piezoelectric phase, in the PVDF-HFP film. Similar to polymeric materials, the composite film is highly processable and can be written into arbitrary shapes or patterns using a pipette or stamping techniques. Finger rubbing or ultrasonication makes the mechanoluminescence patterns readable. This composite mechanoluminescent film provides high potential for future applications in electronic skins, smart electronics, and information encryption techniques.
Large-area Ag nanowires are ordered by spontaneous spreading of volatile droplet on a wettable solid surface. Compared with other nanowires orientation methods, radial shaped oriented Ag nanowires in a large ring region are obtained in an extremely short time. Furthermore, the radial shaped oriented Ag nanowires are transferred and aligned into one direction. Based on the hydrodynamics, the coactions among the microfluid, gravity effect and the adhesion of substrate on the orientation of the Ag nanowires are clearly revealed. This spreading method opens an efficient way for extreme economic, efficient and “green” way for commercial producing ordered nanowire arrays.
Plasmonic Ag nanoparticles were deposited on the silicon pyramid structures to further reduce surface reflectance. Compared with the bare silicon pyramid surface, a dramatic reflectance reduction around 380 nm was observed and the weighted average surface reflectance from 300 nm to 1100 nm could be reduced about 3.4%. By a series of designed experiments combined with Mie theory calculations, the influences of the size, shape and density distribution of Ag nanoparticles on the surface reflectance reduction were investigated in detail. This study shows a practicable method to improve light trapping for the application to solar cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.