The macroscopic optical responses of sculptured thin films (STFs) can be engineered, and the composition and multiscale porosity of STFs can be exploited to promote preferential infiltration by certain chemical and biological species. Accordingly, STFs are attractive as platforms for optical sensing. We considered three aspects of the theory underpinning optical sensing of species which infiltrate STFs: (a) estimation of the constitutive and morphological parameters of infiltrated STFs by means of inverse homogenization; (b) the effect of infiltration on the reflectances and transmittances of infiltrated STFs; and (c) the effect of infiltration on the excitation of surface-plasmon-polariton waves guided by a planar metal/STF interface. Both columnar thin films and chiral STFs were considered. The sensitivity of the optical response of STFs to infiltration was found to bode well for their use in optical sensors.