A magical display has been developed that changes holographic images when it touches water. This new technology allows unlimited imprinting of holographic images, increasing the potential for commercialization.
POSTECH research team led by Professor Junsuk Rho (Department of Mechanical and Chemical Engineering) and Ph.D. Candidates Koh Byung-soo, Young-hwan Yang, Jae-kyung Kim, and Dr. Trebon Budreau have developed a technology for a humidity-responsive display that changes brightness and color depending on humidity.
The team used polyvinyl alcohol (PVA) to successfully create a holographic image with adjustable brightness for the first time. Because this material is so flexible, it is usually used in liquid glues and slimes, and is characterized by swelling when exposed to high humidity. The holographic image is sharp when humidity is low and gradually fades when humidity is high.
The team also developed a display that can arbitrarily adjust the structural colors. A blue image when humidity is low will turn red when humidity is high. By tweaking the humidity, you can express two colors plus all RGB colors.
The study also notes the team’s success in printing images using a single-step nanoimprint technique. It is characterized by the ability to express images clearly even on flexible substrates. In addition, one pixel of this display reaches 700 nm (1 nm = 1/1,000,000,000 m), which is smaller than currently available displays, so it is expected to become a core technology for nanostructured displays.
The findings are of great interest because the newly developed technology could be used in security labels for authentication against counterfeit goods, including food such as whiskey, banknotes and passports. The team is working with the Korea Mint (KOMSCO) to apply optical-based future security technologies to real-world products. This technique is then expected to be applied in the development of hydrogel polymer-based displays that respond to external stimuli such as heat, acidity (pH), and fine dust pollution.
These findings on the tunability of brightness and color in holographic images were published in an international journal Nature Communications When advanced science, Each.
Original: Nanoimprint technology for humidity-responsive holographic images
Than: Pohang University of Science and Technology
