Direct immobilization of biotin on the micro-patterned PEN foil treated by excimer laser.

•Functional groups were drafted to the PEN foil by a laser beam.•Irradiation was performed through a photolithographical mask.•Biotin was covalently immobilized into micron sized spatially defined areas.•A successful affinity fluorometric assay was performed on the modified surface.•An affinity bioanalytical device can be fabricated from the PEN foil substrates.