[ Instrument R & D of Instrumentation Network ] Although infrared radiation is invisible, its utilization rate is very high. It is used in various fields and for various purposes, such as coronavirus detection (ie, through thermal imaging cameras and biosensors). A research team in South Korea has developed an infrared radiation visualization technology to expand its scope of application.
3D conceptual diagram of luminous film. Image source: Korea Institute of Science and Technology (KIST)
The Korea Institute of Science and Technology (KIST, Acting Dean Yin Xizhen) announced that the research team of Dr. Quan Xijun of the Nanophotonics Research Center has developed a multifunctional luminescent film that can visualize near infrared light by wavelength conversion. Infrared light is converted into visible light. The research was conducted by the KIST team and Ko Doo-hyun (principal Han Qingtai), a professor of applied chemistry at Kyung Hee University.
Converting invisible infrared or ultraviolet light to visible light allows us to visually view the data contained in the light, so that infrared or ultraviolet light can be used for displays or imaging devices. Quantum dots recently used in high-definition television can be regarded as a wavelength conversion technology that can convert ultraviolet light into visible light in a display.
The ultraviolet energy is high, which makes it relatively easy to convert into visible light and achieve high conversion efficiency. In contrast, near-infrared light energy is low, and at least two near-infrared photons are absorbed and converted into one high-energy photon. The conversion efficiency of converting near infrared light into visible light is extremely low, about 1/100 to 1/1000 of the efficiency of converting quantum dots into visible light. This is the main obstacle that makes the conversion of near infrared to visible light more realistic for a wider range of applications in sensors, displays, and imaging equipment.
KIST's research team made a square array of silicon oxide (silica) beads decorated with up-converting nanoparticles and metal structures. This configuration maximizes the absorption of near-infrared light and the emission of visible light, thereby improving the conversion efficiency of near-infrared to visible light by nearly 1,000 times.
The lattice structure of the silica microbeads developed by the research team can be easily transferred to the transparent film. This type of film was found to be flexible, foldable, and washable even when the light intensity is maintained after wavelength conversion.
Dr. Kwon Seok-joon of KIST in charge of this research said: "Existing infrared sensors can only collect one type of data, but this technique can be used to collect and visualize various types of data at once. The technology has many advantages in processing, such as foldability, washability and transferability to other films, so its application can be extended to various fields, and can be used for foldable devices, wearable sensors and flexible wavelengths Switch imaging equipment. "
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