Display Changes Holographic Images According to Humidity
Display Changes Holographic Images According to Humidity
  • Reporter Yang Seo-Yeon
  • 승인 2023.01.07 00:04
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▲Nano-scale pixels that change color depending on humidity conditions
▲Nano-scale pixels that change color depending on humidity conditions

There is a “magic display” that changes a hologram image when it holds moisture. It has advanced the possibility of commercialization of displays as it can print holographic images without limit as if stamping them.
Professor Junsuk Rho of the Department of Mechanical and Chemical Engineering, Byoungsu Ko, Younghwan Yang, and Jaekyung Kim of the integrated course, and Dr. Trevon Badloe have developed a new moisture-sensitive display that changes the brightness or color of holographic images depending on the humidity.
Firstly, the research team succeeded in implementing a hologram image that can control brightness using a polyvinyl alcohol (PVA) material. PVA, which is mainly used for water glue or slime due to its flexible nature, has a unique feature that expands as humidity increases. The holographic image, which was clearly visible at low humidity, gradually became blurred as the humidity increased.
Furthermore, the research team developed a display that can freely adjust the color of the hologram image. The hologram image, which was blue when the humidity was low, changed to red as the humidity increased. Fine-tuning the humidity allows it to express RGB colors.
In particular, this study attracts attention by successfully printing holographic images at once using the nanoimprint process. This process can clearly express images even on flexible substrates. In addition, the size of one pixel is 700 nanometers (nm, 1 nm = 1 billionth of a meter), which is smaller than a commercially available display and is considered a key technology in realizing micro displays.
This result is drawing attention since it can can be applied to security labels that determine the authenticity of whiskey, food, bills, and passports. Also, to apply optical-based future security technologies to actual products, the research team continues to cooperate with the Korea Minting and Security Printing Corporation. In the future, it is expected to be applied to the development of hydrogel polymer-based displays that respond to external stimuli such as heat, acidity (pH), and fine dust pollution.
The research results that adjusted brightness were published in the international journal, Nature Communications, and the results that adjusted for color were published in the international journal, Advanced Science.