Micromechanically bending membrane for curved SERS

Planar surface-enhanced Raman scattering (SERS) substrates are widely used in sensing due to their ease of fabrication, reproducibility, and compatibility with lab-on-chip systems. However, their utility can be limited by weak interactions with larger analytes such as macromolecules and cells. Here, we demonstrate how micro-scale curvature enhances lightguiding and improves SERS performance. We designed a micromechanical bending structure (“microbender”) that enables a 150 µm-long membrane to be deflected by 30 µm rotating arms. Fabricated via two-photon polymerization, the microbender preserves the membrane’s planar profile during printing and subsequently permits precise curvature for postfabrication modification. Experimental validation with short (0.8 µm) and tall (4 µm and 6 µm) pillars on the microbender membrane confirmed enhanced SERS signals in the curved state. Notably, 6 µm-tall pillars achieved intensities on par with denser 0.8 µm-tall arrays, illustrating the potential for detecting larger analytes (>1 µm). Beyond SERS, the microbender offers a versatile platform for printing other optical components such as metastructures, microlens arrays, or waveguides. Our findings suggest that curving SERS substrates provides a robust strategy to increase hotspot density, improve light collection, and tailor detection capabilities for diverse applications—especially where standard planar substrates fall short.