Light-matter interactions are commonly described and studied in static systems for which molecular changes do not occur dynamically. Matter-matter interactions on the other hand are described independently from the light interaction phenomena. There is a need for a holistic approach that considers both. Holographic sensors are photonic structures built into polymer film composites that react to molecular interactions with analytes, showing changes in reflectivity and wavelength. These systems are attractive for sensor applications, not only because they easily read by color changes, but also because the light diffraction phenomena are directly related to intermolecular interactions. Here, we describe a theoretical model that couples photonic and molecular mixing phenomena, and demonstrate its experimental validation for holographic sensor systems. (C) 2015 Elsevier B.V. All rights reserved.