Gold nanostructures: A way for their assembling on flexible devices

This study presents the development of a gold nanoparticle island substrate deposited on a polydimethylsiloxane (PDMS) disk. Metal nanoparticles are known for their strong electromagnetic response when illuminated by incident light. In Raman analysis, this phenomenon leads to a significant signal enhancement from molecules adsorbed on the nanoparticles, known as the Surface-Enhanced Raman Scattering (SERS) effect. In medical applications, this enables the detection of biomarkers in complex biological fluids, such as blood or saliva. In recent years, metallic nanoparticles assembled on silicon substrates have been successfully used for spectroscopic analysis, achieving high sensitivity in detecting trace biomolecules in biological mixtures. However, while these rigid devices offer excellent sensor performance, their lack of flexibility makes them unsuitable for direct application to biological samples, which are inherently soft. Here, we demonstrate a flexible PDMS-based plasmonic device. The fabrication process involves a two-step chemical deposition on a pre-patterned PDMS disk to create gold nanoparticle islands. Using a polymeric soft material instead of a semiconductor offers several advantages, including flexibility, transparency, good mechanical properties, and cost-effectiveness. Most importantly, a soft material can conform to biological tissues, enabling direct, on-site applications. The resulting soft device exhibits promising performance, not only for Raman analysis but also as a versatile platform for soft, metal-decorated materials with potential applications in biosensing and flexible electronics.