 We are now living in the world of IoT. We can control all things connected to the internet using a smartphone. In the future after IoT, we'll be living in the world of DOT, Display of Things. Surfaces of all things will be a display, including cars, wallpapers, and even clothes. How can you make display on clothes? It's difficult to apply current LCD or LED technology, so we need a different technology. We can get a hint from nature by looking at chameleon. In fact, chameleon skin is a LED well-developed wearable display. The chameleon shows all the colors of the rainbow. Surprisingly, however, they do not use any color pigment. Instead, they use a regular array of granite particles. The raptors reflect the specific wavelength of the jubilee, and color can be changed by varying how tightly the raptors are arranged. If we can artificially create chameleon skin, it would be a disruptive technology for DOT. We have used uniformly sized nanoparticle to build a regular array that develops color without any chemical pigment. Now with a single set of material, we can make all visible colors. All poles have a crystal structure and show striking colors through the same principle. If we make one centimeter size of a pole by assembling one particle per second, it would take 32 million years. How can you then create such a regular crystal structure in a short time? We can harness the power of colloidal science. This describes how particles spontaneously form a regular crystal structure when they are all repelling each other. Because they want to minimize total repulsive energy that they feel, the natural outcome is that they form a regularly spaced array. So we have formulated ink that has this property. Our ink is carried in a resin that hardens when exposed to UV light. Therefore, once colloidal particles form a regular structure by repulsion, we can immediately stabilize the structure by exposing it to UV light to redefine the resin. The fumes of colloidal crystals show beautiful color even though there isn't a single chemical pigment inside. The so-called structural colors are only developed by the reflection of selected wavelengths of light by the crystal structure. The structural colors are reflective and iridescent. The colloidal crystal can be tailored to have any colors and pattern. For example, we made an apple tree, RGB pixel in a microscale, and Olympic emblem in a centimeter scale. These colors are all made of same material without use of any chemical pigment. Structural color pattern can be used for anti-counterfeiting. This beautiful green color shifts the blue depending on the observation angle and can be transparent at other angles allowing for visual inspections of ostenticity. Moreover, invisible optical barcodes offer an additional layer of security. Color contact lenses are popular but some of the chemical pigments are potentially toxic to eye. This color contact lens, made using colloidal crystal, does not have any chemical pigment and provide iridescent colors. These three images are from the same contact but observed at different angles. The example I showed so far have a fixed color. How can it then create color-tunable artificial chameleon skin? One possible way is to make colloidal crystal in an elastomeric matrix. The two materials show changing color when they are stretched or compressed just as in chameleon. Now we are developing the device that can stretch or compress the elastomer in areas of our choosing. The puttonic elastomer in the combination with the device can be applied to your card, wallpapers, and clothes to convert them into displays. At the same time, we are also considering other ways to change crystal structure in real time. For example, some polymers are sensitive to electric field and if they are used as a matrix of colloidal crystal, their color could be tuned with an electric field. Technology on structural coloration is still growing. Who knows when material and mechanism will finally survive for DOT? I hope my research, inspired by this chameleon, helps the development of a new display technology for DOT world and hope you can wear color-tunable clothing in near future. Thank you.