Highly Efficient Light‐Trapping 3D Plasmonic Au Cone‐Arrays‐in‐Bowl (CAIB) for Simultaneous SERS Measurement in Pump‐Free Microfluidic Device

This study presents the development of a novel highly efficient light-trapping 3D Au plasmonic cone-arrays-in-bowl (CAIB) surface-enhanced Raman scattering (SERS) platform. The innovative platform integrates a pump-free microfluidic device with a highly sensitive SERS detection system. The CAIB structures are fabricated using a combination of techniques, including polystyrene sphere self-assembly, inductively coupled plasma etching, and electron beam deposition. These hierarchical structures, consisting of nanocone arrays regularly embedded in microbowl cavities, provide an extensive distribution of hot spots, resulting in enhanced sensitivity and reproducibility. Furthermore, an integrated pump-free microfluidic chip is developed, capable of autonomous seawater transport via capillary action to adapt this technology for marine monitoring. This design eliminates the need for an external pump, significantly improving the system's portability and facilitating on-site detection of heavy metals at various concentrations. The integrated SERS-based pump-free microfluidic device demonstrated remarkable sensitivity, achieving detection ranges of 10^-7-10^-12 m for both Hg²⁺ and Pb²⁺ heavy metal ions in seawater. It is believed that this high-performance, plasmonic platform represents a significant advancement in light-trapping materials and environmental monitoring technologies.