Photonic Rubber Sheet Displays Tunable Structural Color

Daniel S. Burgess

An elastic photonic crystal developed by scientists at the National Institute for Materials Science in Tsukuba, Japan, demonstrates a shift in its apparent color under an applied strain, suggesting its utility in strain imaging and mechanical sensors. In tests, the shift in the color peak was reversible over several deformation cycles, and the material did not exhibit signs of deterioration.

The elastic photonic crystal exhibits structural coloration by Bragg diffraction. Under mechanical strain, its peak wavelength is blueshifted.

The photonic crystal comprises 202-nm-diameter polystyrene spheres arrayed in a cubic close-packed array in an elastomer. It exhibits structural coloration by Bragg diffraction, with a peak wavelength at approximately 590 nm under no strain.

As the material is stretched, the peak wavelength is blueshifted, until it reaches approximately 560 nm under an elongation of 20 percent. When the elastic sheet is released, the peak wavelength returns to its initial value.