Label-free porous silicon membrane waveguide for DNA sensing

Abstract

We report a label-free porous silicon membrane waveguide biosensor based on a 1μm thick freestanding porous silicon film with 100nm diameter pores. The sensor operates in the Kretschmann configuration. A formvar polymer film provides robust adhesion of the porous silicon membrane to a rutile prism and enables confinement of guided modes in the porous silicon membrane. Attenuated total reflectance measurements are performed, along with theoretical calculations, to fully characterize the waveguide. The sensitivity of the sensor is investigated through DNA hybridization in the porous silicon membrane. A detection limit of 42nM was demonstrated for 24-base pair DNA oligonucleotides.