(a) Schematic representation of the SERS sensing mechanism, showing molecules trapped in the nanogap. (b) Schematic diagram of the transfer process of nanogaps with micrometer periodicity onto a flexible substrate. FE-SEM images of the top view of the nanogap (c) before and (d) after strain (scale bars: 10 µm). (The inset shows a close-up of a single gap from the top, (scale: 1 µm). Credit: Advanced Optical Materials (2025). DOI: 10.1002/adom.202403021
A research team affiliated with the Nano Optics Group within the Department of Physics at UNIST has announced the successful implementation of a plasmonic structure capable of precisely adjusting nanometer-sized gaps in response to temperature changes. This technology enables real-time adjustment of nanogaps to match the size of molecules, allowing for detection capabilities that significantly surpass conventional sensors.
The research findings have been published online in Advanced Optical Materials.
The flexible nanogap structures developed in this research serve as a key component in Surface-Enhanced Raman Spectroscopy (SERS). SERS is an analytical technique that utilizes a strong near-field created by localized surface plasmon resonance induced by incident light on metallic nanostructures based on gold thin films, amplifying Raman signals of molecules millions of times.
By employing flexible substrates, researchers have achieved the dynamic modulation of nanogaps, thus opening up the possibility of effectively analyzing various sizes of molecules that were previously challenging to assess.
The research team successfully developed a method for adjusting nanogaps through temperature control, achieving a remarkable enhancement factor of approximately 10⁷ in SERS signals and reaching a detection limit as low as 10⁻¹² M, suitable for single-molecule detection.
Dr. Mahsa Haddadi Moghaddam, who led the research, stated, "The ability to precisely control nanogaps using temperature changes allows us to achieve much higher sensitivity than conventional SERS sensors. This technology has significant potential, particularly for accurate analyses at the single-molecule level and in various environmental and medical diagnostic applications."
More information: Mahsa Haddadi Moghaddam et al, Tuning 1D Plasmonic Gap at Nanometer Scale for Advanced SERS Detection, Advanced Optical Materials (2025). DOI: 10.1002/adom.202403021
Provided by Ulsan National Institute of Science and Technology
