A porous material was considered as a platform for optical sensing. It was envisaged that the porous material was infiltrated by a fluid that contains an agent to be sensed. Changes in the optical properties of the infiltrated porous material provide the basis for detection of the agent to be sensed. Using a homogenization approach based on the Bruggeman formalism, wherein the infiltrated porous material was regarded as a homogenized composite material, the sensitivity of such a sensor was investigated. For the case of an isotropic dielectric porous material of relative permittivity and an isotropic dielectric fluid of relative permittivity , it was found that the sensitivity was maximized when there was a large contrast between and ; the maximum sensitivity was achieved at midrange values of porosity. Especially high sensitivities may be achieved for close to unity when , for example. Furthermore, higher sensitivities may be achieved by incorporating pores that have elongated spheroidal shapes.
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