Development of silicon-on-insulator-based nanoporous silicon photonic crystals for label-free DNA detection

We fabricated a one-dimensional nanoporous silicon photonic crystal on a silicon insulator substrate by a cost-effective electrochemical method as an optical biosensor for the detection of DNA hybridization. In the first step, a transfer matrix method was used to calculate the corresponding reflectivity spectrum for the design of nanoporous silicon photonic crystals. Then silicon-on-insulator-based photonic crystals were prepared by a novel simple electrochemical etching. Genes were hybridized inside the porous silicon (PS) pores by aminopropyltriethoxysilane and glutaraldehyde and detected through frequency resolved reflectance measurements. A detection sensitivity of 17.445  nm/μM is demonstrated with good specific detection. The linear response range covers a concentration range of antifreeze protein gene from 0.625 to 10.000 μM. This high responsivity indicates that the silicon-on-insulator-based PS photonic crystal has significant potential for application in biological micro-electro-mechanical-systems technologies.