Porous materials offer several advantages for chemical and biomolecular sensing applications. In particular, nanoscale
porous materials possess a very large reactive surface area to facilitate the capture of small molecules, and they have the
capability to selectively filter out contaminant molecules by size. This paper will provide an overview of the fabrication,
functionalization, and application of porous silicon thin films and waveguides, as well as porous gold templates, for the
detection of small chemical and biological molecules. Issues of efficient molecule infiltration and capture inside porous
materials, binding kinetics in nanoscale pores, the influence of pore size on small molecule detection sensitivity, and the
new nanoscale patterning technique of Direct Imprinting of Porous Substrates (DIPS) will be addressed. Additionally, a
novel application of porous silicon for detection of x-ray radiation will be introduced.
A porous silicon waveguide with integrated grating coupler is demonstrated as a new platform for portable detection of chemical and biological molecules. The two-layer porous silicon waveguide is formed by electrochemical etching and a photoresist grating is fabricated directly on the waveguide core by means of electron beam lithography. Angle-resolved reflectance measurements reveal distinct peaks corresponding to the guided mode. A 0.420° reflectance shift was observed upon 16-base DNA hybridization, which was more than a factor of 5 larger than the observed reflectance shift after exposure to a mismatched DNA sequence.