Flexible Plasmonic Polymeric Membranes Consisting of Gold Nanoparticle Clusters as a Platform for Biomedical Sensing

Flexible plasmonic platforms are increasingly sought after for wearable and implantable biosensing, yet current solutions are often costly or mechanically fragile. In this work, we present a scalable and low-cost method to fabricate fully flexible plasmonic substrates by combining ultrathin PDMS membranes with patterned amorphous silicon layers. Nanopatterning, achieved via soft lithography, enables localized growth of gold nanoparticle clusters through electroless deposition, ensuring strong plasmonic activity while maintaining mechanical adaptability. The resulting membranes easily conform to curved surfaces and enable sensitive fluorescence and Raman detection of biomarkers, such as IgG (100 pg/mL) and IL-8 (1 ng/mL). The device also operates effectively in an inverted configuration, which is a key feature for wearable integration. FEM simulations confirm the plasmonic field enhancement, highlighting the robustness of the design.