Chiral sculptured thin films for optical sensing of analytes in fluids

Chiral sculptured thin films (CSTFs) are attractive potential platforms for optical sensing because their porosity, morphology, and optical properties can be tailored to order. For this application’ it is envisaged that a CSTF is made of a dielectric material and that the analyte is carried into the void regions of the CSTF by a fluid such as water. The presence of such analytes may be sensed by a shift in the circular Bragg phenomenon or the ex citation of multiple surface plasmon-polariton waves at the planar interface of the CSTF and a metal film. Empirical theoretical models were developed to explore these two sens ing scenarios. Our approach utilized an inverseforward homogenization procedure, depending on the Bruggeman homogenization formalism, to estimate the constitutive parameters of infiltrated CSTFs. The sensitivities revealed in numerical studies bode well for the future development of such optical sensors.