A colorimetric resonant mesoporous silicon photonic crystal is used as a surface binding platform for biochemical
detection. The photonic crystal, when illuminated with white light at normal incidence, is designed to reflect a photonic
band gap (PBG) centered at a single wavelength. When molecules are attached to the internal surfaces of pores, the PBG
is shifted due to the change in refractive index of the porous silicon layers. The planar structure of the platform can be
easily integrated into a fluidic cell. We have optically verified the presence of proteins and chemicals as a colorimetric
shift in the reflectivity spectrum of mesoporous silicon photonic crystals and microcavities.