Fused silica-capillaries were functionalised with spiropyran-polymer brushes using a spiropyran functionalised norbornyl derivative as the monomer (SP-M). The polymerisation was achieved by surface-initiated ring-opening metathesis polymerisation (Si-ROMP). We obtained a three dimensional arrangement, covalently attached to the inner wall of the fused-silica capillary, where the spiropyran moiety has the freedom to open and close in response to light (UV, white light). The spiropyran moieties present a very strong dependence on the polarity of the solvent what is expressed by a shift in its main UV-Vis absorption band therefore functionalised capillaries were successfully used to photo-detect solvents of different polarity while passing through the capillary.