2022/04/19
Keio University
Japan Science and Technology Agency (JST)
Kanagawa Institute of Industrial Science and Technology
A research group led by Professor Hideyuki Maki and Visiting Researcher Tetsuma Nakagawa of the Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, along with Yui Shimura from the master's program at the same university, has developed a new infrared analysis technology based on a novel principle using multilayer graphene light source chips. This technology not only enables low-cost and compact infrared analysis by using multilayer graphene light source chips but also achieves extremely high spatial resolution infrared imaging that surpasses the spatial resolution of conventional Fourier-transform infrared spectroscopy (FT-IR) and the theoretical "diffraction limit."
Analytical technology is crucial not only in basic research and industrial fields but has also become important in recent years as a familiar technology for applications such as diagnosing diseases and pathogens and for environmental analysis. Among these, analytical techniques using infrared light, such as FT-IR, are one of the most well-known analytical methods. Because they can directly provide information on material structure, they are widely used as a marker-free analysis method in various fields, including chemistry, materials, environmental science, and biotechnology. However, current FT-IR systems use macroscopic, millimeter-scale infrared light sources like halogen lamps and ceramic light sources. This, combined with the theoretical limitation known as the diffraction limit, results in a low spatial resolution of about 10 µm, making high-resolution imaging and micro/trace analysis, comparable to that of visible light, difficult.
In this study, we originally developed an on-chip infrared light source using extremely small multilayer graphene, as small as 500 nm square, and performed infrared analysis by bringing the analysis sample into direct proximity with the graphene light source chip. As a result, despite the light source being extremely small, with an emission area one-millionth that of conventional FT-IR light sources, it was capable of performing infrared analysis comparable to commercial FT-IR systems. Furthermore, using a new principle that utilizes the near-field generated by the light source itself, we demonstrated an extremely high spatial resolution (1 µm) that surpasses the diffraction limit. By using this technology, imaging and trace analysis with visible-light-level resolution become possible in the infrared region without the need for large and expensive infrared light sources such as lasers. This is expected to lead to the creation of entirely new infrared analysis technologies in various fields, including medicine, biotechnology, new materials development, and environmental analysis.
This research was conducted with support from Grants-in-Aid for Scientific Research, the JST A-STEP (Adaptable and Seamless Technology Transfer Program through Target-driven R&D) industry-academia collaborative (nurturing type) program, and the Strategic Research Seed Incubation Project of the Kanagawa Institute of Industrial Science and Technology (KISTEC).
The results of this research were published online in the American Chemical Society (ACS) journal "Nano Letters" on April 18, 2022 (local time).
For the full press release, please see below.