Highly sensitive refractive index sensing based on nanostructured porous silicon interferometers

In this study, we present the experimental evidence demonstrating the utility of electrical double layer (EDL)-induced ion accumulation, using sodium (Na+) ion in water as a model substance, on a negatively charged nanostructured surface, specifically thermally grown silicon dioxide (SiO2). This novel approach, termed Ion Surface Accumulation (ISA), aims to enhance the performance of nanostructured porous silicon (PSi) interferometers in optical refractometric applications.