Volume detection based on porous silicon waveguide for CO mid-infrared spectroscopy.

A mid-infrared (mid-IR) porous silicon (PSi) waveguide gas sensor was fabricated. PSi guiding and confinement layers were prepared by electrochemical anodization. Ridge waveguides were patterned using standard i-line photolithography and reactive ion etching.

Detection of SARS-CoV-2 N protein using AgNPs-modified aligned silicon nanowires BioSERS chip.

The SARS-CoV-2 (COVID-19) pandemic had a strong impact on societies and economies worldwide and tests for high-performance detection of SARS-CoV-2 biomarkers are still needed for potential future outbreaks of the disease. In this paper, we present the different steps for the design of an aptamer-based surface-enhanced Raman scattering (BioSERS) sensing chip capable of detecting the coronavirus nucleocapsid protein (N protein) in spiked phosphate-buffered solutions and real samples of human blood serum. Optimization of the preparation steps in terms of the aptamer concentration used for the functionalization of the silver nanoparticles, time for affixing the aptamer, incubation time with target protein, and insulation of the silver active surface with cysteamine, led to a sensitive BioSERS chip, which was able to detect the N protein in the range from 1 to 75 ng mL in spiked phosphate-buffered solutions with a detection limit of 1 ng mL within 30 min.

Theoretical Demonstration of the Interest of Using Porous Germanium to Fabricate Multilayer Vertical Optical Structures for the Detection of SF Gas in the Mid-Infrared.

Porous germanium is a promising material for sensing applications in the mid-infrared wavelength range due to its biocompatibility, large internal surface area, open pores network and widely tunable refractive index, as well as its large spectral transparency window ranging from 2 to 15 μm. Multilayers, such as Bragg reflectors and microcavities, based on porous germanium material, are designed and their optical spectra are simulated to enable SF gas-sensing applications at a wavelength of 10.55 µm, which corresponds to its major absorption line.

Application of Doehlert Matrix for an Optimized Preparation of a Surface-Enhanced Raman Spectroscopy (SERS) Substrate Based on Silicon Nanowires for Ultrasensitive Detection of Rhodamine 6G.

In this work, we combined a hierarchical nano-array effect of silicon nanowires (SiNWs) with a metallic surface of silver nanoparticles (AgNPs) to design a surface-enhanced Raman spectroscopy (SERS) scattering substrate for sensitive detection of Rhodamine 6G (R6G) which is a typical dye for fluorescence probes. The SiNWs were prepared by Metal-Assisted Chemical Etching (MACE) of n-Si (100) wafers. The Doehlert design methodology was used for planning the experiment and analyzing the experimental results.

High sensitivity optical biosensor based on polymer materials and using the Vernier effect.

We demonstrate the fabrication of a Vernier effect SU8/PMATRIFE polymer optical biosensor with high homogeneous sensitivity using a standard photolithography process. The sensor is based on one micro-resonator embedded on each arm of a Mach-Zehnder interferometer. Measurements are based on the refractive index variation of the optical waveguide superstrate with different concentrations of glucose solutions.