Direct laser writing of curved SERS for light-guided enhancement

Flexible SERS substrates, typically used on irregular surfaces, have unexplored optomechanical effects that could enhance performance. We developed a micromechanically bending structure, i.e. microbender, to study how bending affects SERS substrates’ performance. Optical simulations of nanopillar arrays on micro-curved surfaces showed a 25–134 % improvement in mean-field localization at the pillar tips for arrays with pillar diameters of 0.4–1 μm, pitches of 0.5–0.8 μm, and heights of 0.5–4.5 μm. Raman measurements showed that SERS intensity increases when in a curved state due to enhanced light scattering, guiding, and field localization. A curved array of 6 μm tall pillars (0.5 μm diameter, 1 μm spacing) produced Raman intensities similar to dense single-voxel arrays with shorter 0.8 μm pillars (0.2 μm diameter, 0.2 μm gaps) in the planar state. This finding suggests that low resolution fabrication technologies can produce curved SERS substrates with similar performance to high resolution planar SERS, offering an alternative to the current “smaller is better” trend through post-fabrication manipulation. Planar SERS substrates have improved performance when curved. This study introduces a microbender structure fabricated with 2-photon polymerization-based direct laser writing to study curved SERS, demonstrating improved field localization and SERS intensity in curved states. [Display omitted] •Design and fabrication of a microscale bending structure to achieve curved membranes.•Exploring nanostructure parameters' effect on curved SERS performance via simulations.•Experimental comparison of SERS performance in planar and curved states.•Curved SERS enhances field localization and light-guiding.