Hierarchical electrohydrodynamic structures for surface-enhanced raman scattering

Surface enhanced Raman scattering (SERS) is a well-established spectroscopic technique that requires nanoscale metal structures to achieve high signal sensitivity. While most SERS substrates are manufactured by conventional lithographic methods, the development of a cost-effective approach to create nanostructured surfaces is a much sought-after goal in the SERS community. Here, a method is established to create controlled, self-organized, hierarchical nanostructures using electrohydrodynamic (HEHD) instabilities. The created structures are readily fine-tuned, which is an important requirement for optimizing SERS to obtain the highest enhancements. HEHD pattern formation enables the fabrication of multiscale 3D structured arrays as SERS-active platforms. Importantly, each of the HEHD-patterned individual structural units yield a considerable SERS enhancement. This enables each single unit to function as an isolated sensor. Each of the formed structures can be effectively tuned and tailored to provide high SERS enhancement, while arising from different HEHD morphologies. The HEHD fabrication of sub-micrometer architectures is straightforward and robust, providing an elegant route for high-throughput biological and chemical sensing. Electrohydrodynamic (EHD) instabilities are employed to create hierarchical structures including, pillars, coaxial morphologies and rims with sub-micrometer edges, which are further used as substrates for surface-enhanced Raman scattering (SERS). 1.0 × 10 SERS enhancements from isolated rims and coaxial patterns are observed. Since SERS enhancement arises from each of the isolated structures in the array, EHD-patterned substrates provide optimal platforms for high-throughput SERS detection, where each of the individual EHD structures can be used to detect a different molecular component.