Silicon Nanowire Optical Rectangular Waveguide Biosensor for DNA Hybridization

Silicon nanowire optical rectangular waveguide (SNORW)-based biosensor is proposed for the first time to detect deoxyribonucleic acid (DNA) hybridization. It works on the principle of detecting the change in refractive index during the hybridization process when double strand DNA splits into single strands of DNA or two single strands renaturate into a double strand DNA. Considering the fabrication on 220- and 330-nm silicon technology, first a typical configuration of SNORW is optimized to provide physical compactness and high-power confinement. Next, parameters characterizing link layer and DNA are added, and change in power confinement is ascertained when double strand DNA (dsDNA) splits into two single strand DNA (ssDNA) or two ssDNA renaturate to form a dsDNA. A mean to enhance the difference in power confinement in the presence of 100% ssDNA and 100% dsDNA is also proposed. As the splitting/renaturation of DNAs is a slow process, power confinement when different percentages of dsDNA and ssDNA coexist is also evaluated.