The unclose-packed photonic crystal (PC) gels self-assembled by electrostatic interaction between the colloidal particles were obtained by recentrifugation and redispersion methods to remove the ionic impurities. The unclose-packed PC gels were fabricated by locking the ordered structures of the unclose-packed PC using the in situ polymerization of acrylamide monomers. The diffraction peak wavelengths of the unclose-packed PC gels can cover the visible light regions. The pressure sensitivity of the unclose-packed PC gels based on the response to the changes of the pressure on the hydrogel was also reported. The diffraction peak wavelengths of the unclose-packed PC gels were varied with the added pressures. The results imply that the unclose-packed PC gels have potential applications to visual detections.

Key words: photonic crystal, hydrogel, pressure sensitivity, visual detection