Fabrication of 2D metal nanoparticle array encapsulated by anodic aluminum oxide and its applications to surface-enhanced Raman scattering

This paper describes the verification of a reproducible, highly sensitive, robust, and reliable SERS active substrate that is composed of periodic silver nanoparticle arrays encapsulated within large-area (1 in ²) anodic aluminum oxide films. The well-organized spherical silver nanoparticles are electro-deposited at the interior bottom of alumina nanochannels. After chemically removing the residual aluminum, the exposed bottom alumina layer can be adopted as a sensitive SERS sensor but can avoid the oxidation and sulfidation corrosion of embedded silver. The encapsulated nanoparticle arrays provide strong and reproducible SERS signals of probe R6G and adenine molecules. The shelf life of the single-process fabricated SERS substrate is examined and over two months with repeatable SERS measurements and reproducible SERS signals. Avoiding the complicated and more expensive vacuum deposition process, the cost-effective and single electrochemical process fabricated SERS active substrate which can retain the most compromise Raman enhancing power and repeatable uses for at least two months is a promising sensor for a variety of practical applications.