Macroscopic mechanical perturbations have been observed to result in optical changes for certain compounds and composite materials. This phenomenon coâ¦
By layering tiny nanospheres onto stretchy fabric, scientists have created a material that changes color when stretched. Called "polymer opal" by the team, the material mimics the multicolored brilliance of an opal gemstone. Now, using ink made from synthetic photonic crystals and a printer that can... Read more
Handy for bags but this stuff could also save lives if they get it right -https://www.sciencedirect.com/science/article/abs/pii/S0928493114005128
Found it, this is the stuff.