Dr. Hiroshi Fudouzi

Research theme:
Tunable structural color of opal materials: Inspired from the mechanism of reflecting platelets in a tropical fish

It is well known that living things uses the structural color, for example, in the outer shells of jewel beetles, wings of Morpho-butterfly, peacock feathers and many kinds of insects. In addition, a certain kind of fish and the mammal can change a structural color on the surface of the skin. Figure 1 shows a regular arrangement of reflectance plates with high a refractive index is located in the low refractive index of cytoplasm. The structural color changes when the spacing between these reflectance plates increases or decreases, a motile iridophore. The color of skin on the damselfish reversibility and quickly change between blue and green. The color tuning mechanism gave us a new idea for design of smart material with tunable color.

We have been working on closely packed colloidal crystals and their applications. Colloidal crystals, 3D ordered array particles, are fabricated by self-assembly and low energy efficient consumption process. The particles array diffracts light of selective wavelengths according to Bragg’s law. This causes a structural color of the colloidal crystals, opal materials. Figure 2 shows opal material with tunable structural color by mechanical deformation. A structural color changes into this material reversible like the cobalt blue. The illustration C shows the color change caused by a variable spacing of the lattice distance of the particle arrays.

Figure 1 A tropical fish of cobalt blue and tuning mechanism of structural color by motile iridophore.

Figure 2 An elastic colloidal crystal film coated on a rubber sheet enables change structural color from red (A) to green (B). The mechanism of tuning color by elastic deformation (C).


Senior Researcher, Hiroshi Fudouzi, PhD
Optronic Materials Center
National Institute for Materials Science
1-2-1 Sengen, Tsukuba 305-0047, Japan




  • National Institute for Materials Science
  • Competence in Bionics
  • The Clay Science Society of Japan