A novel technique for rapid and ultrahigh sensing of heavy metals in aqueous media based on microfluidic platform coated with Porous Anodic Alumina (PAA) membrane and functionalized with ultrathin porous layer of highly ordered hexagonal arrays of Au nanoparticles with 25nm sub-gaps is proposed. The sensor demonstrated high selectivity between three different heavy metals (Hg, Cd, and Pb) with concentrations varied from 1 to 20 ppb. The platform provides an instant and fully integrated detection method that is based on in situ surface-enhanced Raman scattering (SERS) spectroscopy. The observed Raman enhancement is due to the excitation and interference of surface plasmon waves, which are highly dependent on the type and concentration of the heavy metal. As a result, the proposed sensor is an unprecedented fully integrated platform that is easy to fabricate and can be seamlessly integrated with an in situ signal detection device for added functionality.
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