Wafer-Scale Flexible Plasmonic Metasurface With Passivated Aluminum Nanopillars For High-Sensitivity Immunosensors

Aluminum has recently attracted significant interest as a promising alternative material to noble metals for plasmonic metasurface biosensing, but it suffers from surface oxidation and higher visible-light loss, which is usually believed to limit its capability of sensing. We report here that the large-area flexible passivated Al nanopillar metasurface shows better bulk and surface sensing performance than Au nanopillar metasurface. Compared to the Au metasurface, the existance of superficial alumina layer protects the Al metasurface from further oxidation and maintains the high surface sensitivity. In the test for the antibody of bovine serum albumin, the Al-based metasurface demonstrates a much higher sensitivity by two orders of magnitude versus the Au counterpart. Its detection of limit is as low as 1 pg/mL, which implies a great potential for clinical diagnosis. Our study paves the way for the use of Al metasurface in low-cost high-performance biosensing of mobile healthcare.