KAIST: "Ultra-Miniature Infrared Sensors Fabricated via 3D Printing"

A technology that enables the fabrication of "ultra-miniature infrared sensors" in desired shapes and sizes using room-temperature three-dimensional (3D) printing has been developed for the first time in the world by a Korean research team.

KAIST announced on November 3 that a research team led by Professor Kim Ji-tae from the Department of Mechanical Engineering, in collaboration with Professor Oh Seungjoo from Korea University and Professor Tianshu Zhao from the University of Hong Kong, has developed a 3D printing technology capable of producing ultra-miniature infrared sensors smaller than 10 micrometers at room temperature.

(From left) Ji-Tae Kim, Professor at KAIST; Seung-Joo Oh, Professor at Korea University; Tianshu Zhao, Professor at the University of Hong Kong. Provided by KAIST

Infrared sensors are essential components that convert invisible infrared signals into electrical signals. As indispensable elements in implementing next-generation electronic technologies in various fields such as robotic vision, their role in achieving miniaturization, lightweight design, and diverse form factors for sensors is becoming increasingly significant.

However, conventional manufacturing methods based on semiconductor processes are advantageous for mass production but have posed barriers to flexibly responding to rapidly changing technological demands. Above all, the necessity of high-temperature processing has limited material choices and resulted in high energy consumption.

To address these issues, the research team developed an ultra-precise 3D printing process that creates metal, semiconductor, and insulator materials as nanocrystalline liquid inks and stacks them layer by layer on a single printing platform.

This breakthrough enables the direct fabrication of core components of infrared sensors at room temperature, making it possible to realize ultra-miniature sensors in customized shapes and sizes.

In particular, the team applied a "ligand exchange" technique during the 3D printing process, which replaces insulating molecules on the surface of nanoparticles with highly conductive ones, thereby achieving excellent electrical performance without high-temperature thermal treatment. As a result, the researchers emphasize that it is now possible to produce ultra-miniature infrared sensors as small as one-tenth the thickness of a human hair (less than 10 micrometers).

Professor Kim stated, "The three-dimensional printing technology developed by our joint research team will not only enable further miniaturization and weight reduction of infrared sensors but also serve as a catalyst for the development of innovative form-factor products that were previously unimaginable. Most importantly, the ability to reduce the massive energy consumption associated with high-temperature processing will lower production costs and realize environmentally friendly manufacturing processes, contributing to the sustainable development of the infrared sensor industry."

This research was supported by the Ministry of Science and ICT's Excellent Young Researcher Program, the National Strategic Technology Materials Development Program, and the International Collaboration Program for Fundamental Technology. The results (paper) were recently published online in "Nature Communications."