A technology has been developed for the first time in the world that can be used to create transparent displays and augmented reality (AR) devices by reproducing the physical phenomena of a chameleon's ever-changing skin color or a peacock's beautiful feather colors using nano 3D printing.

Dr. Jae-yeon Pyo's team at the Korea Electrotechnology Research Institute (KERI) Smart 3D Printing Research Team announced on the 7th that they have successfully implemented a three-dimensional diffraction grating capable of controlling the path of light using "nano 3D printing technology." This new technology can utilize the principles of structural color observed in nature in advanced display technology.

When light encounters microscopic structures at the wavelength level (1/100 to 1/1,000 the thickness of a human hair), it diffracts and changes its path. If these microscopic structures exhibit regularity, diffraction can reflect only light of a specific wavelength, producing a color. This is called "structural color." Examples observed in nature include the skin color of a chameleon, which changes structural color not due to multiple pigments but by changing the microstructure of the skin, and the feathers of a peacock show beautiful structural color due to the characteristic arrangement of internal microstructures.

KERI's achievement is the implementation of a "diffraction grating," capable of precisely controlling structural color, using nano 3D printing technology. A diffraction grating is a device with a regular arrangement of microscopic structures, such as parallel lines, for the purpose of controlling light diffraction. When light is shone onto this grating, it reflects along different paths depending on its wavelength, generating structural color or a spectrum. In other words, this technology utilizes 3D printing technology to control light and precisely reproduce nature's beautiful structural color without the use of dyes.

Controlling the diffraction of light, whose wavelength is only 1/1000th the width of a human hair, requires an extremely fine diffraction grating. KERI, which possesses world-class nano 3D printing technology, has successfully printed a high-density nanowire diffraction grating using a novel approach called "lateral printing." This method involves moving a 3D printing nozzle, as if sewing, to print multiple lines of bridge-shaped diffraction gratings.

The newly developed diffraction grating is expected to find wide application in advanced display fields. The inherent transparency of the diffraction grating makes it ideal for use in future transparent displays, such as smart windows, mirrors, and automotive head-up displays. Furthermore, it can be applied in a variety of ways to augmented reality (AR) devices, which already utilize diffraction gratings as a core component. Furthermore, diffraction gratings can be designed to exhibit different colors depending on their deformation, making them useful in mechanical engineering and biomedical fields that require deformation detection, and can be utilized in various optical physics studies as diffraction gratings themselves.

KERI's Dr. Jae-yeon Pyo said, "This is a world-class 3D printing technology that accurately implements the desired structural color in the desired location without restrictions on the material or shape of the substrate," and added, "It will be able to overcome the limitations of the standardized 'form factor' of display devices and bring about diversification of shapes."

The results of this research were recognized for their excellence and were published as a cover paper in ACS Nano, a top-tier SCI journal in materials science published by the American Chemical Society. The journal's JCR Impact Factor, which measures the journal's influence, was 17.100, placing it in the top 5.7% of its field.

Having completed the patent application for the original technology, KERI anticipates that this achievement will garner significant attention from display-related companies and plans to identify companies in need and promote technology transfer.

Meanwhile, KERI is a government-funded research institute under the National Research Council of Science and Technology, Ministry of Science and ICT. This research was conducted as part of KERI's core project, "Development of Integrated 4D Printing Technology for Electrical and Electronic Device Circuits and Housings." Dr. Pyo Jae-yeon also serves as an adjunct associate professor at the University of Science and Technology (UST).