Rapid fabrication of colloidal crystal films by electrophoretic deposition and its application for a volatile liquid and strain detection sensor

High-speed fabrication of colloidal crystal films composed of polystyrene particles was attempted by electrophoretic deposition. Flat, uniform colloidal crystal films were fabricated on ITO-coated glass or PET sheet substrates in several minutes by using an optimum ratio of a mixed solvent of water and ethanol. The obtained colloidal crystal films exhibited structural color predicted from the particle size. The structural color of the colloidal crystals immobilized by immersing silicone elastomer changed to different colors when the interlayer spacing was changed due to the swelling/shrinkage by dropping organic solvents or applying tensile stress on the films. Such structural color changes were applicable for a simple sensor to visualize strain.