Tuning 1D Plasmonic Gap at Nanometer Scale for Advanced SERS Detection

Abstract The “hotspots”, which are typically found in nanogaps between metal structures, are critical for the enhancement of the electromagnetic field. Surface‐enhanced Raman scattering (SERS), a technique known for its exceptional sensitivity and molecular detection capability, relies on the creation of these hotspots within nanostructures, where localized surface plasmon resonance (LSPR) amplifies Raman signals. However, creating adjustable nanogaps on a large scale remains challenging, particularly for applications involving biomacromolecules of various sizes. The development of tunable plasmonic nanostructures on flexible substrates represents a significant advance in the creation and precise control of these hotspots. This work introduces tunable nanogaps on flexible substrates, utilizing thermally responsive materials to allow real‐time control of gap width for different molecule sizes. Through advanced nanofabrication techniques, uniform, tunable nanogaps are achieved over large areas of wafer scale, enabling dynamic modulation of SERS signals. This approach results in an enhancement factor of over ≈10⁷, sufficient for single‐molecule detection, with a detection limit as low as 10⁻¹ ² m . The thermally tunable nanogaps provide a powerful tool for the precise detection of molecules and offer significant advantages for a wide range of sensing and analytical applications.