Large-Area Flexible SERS Sensor Chips Fabricated Using a Combination of Nanosphere Self-Assembly and Glancing Angle Deposition for Chemical and Biological Sensing.

In this work, we combine two highly efficient nanofabrication methods, nanosphere lithography (NSL) and glancing angle deposition (GLAD), to fabricate large-area and low-cost surface-enhanced Raman scattering (SERS) substrates consisting of highly ordered arrays of pointed plasmonic nanowires, such that the size of the plasmonic nanowires as well as the gaps between the nanowires can be precisely controlled. These SERS substrates are cut into small SERS sensor chips for highly sensitive, selective detection of analyte molecules of interest, including pesticides thiabendazole, paraoxon-ethyl, and phosmet and nucleotides adenine and thymine. Moreover, this paper reports the fabrication of SERS substrates on flexible polymeric films using a combination of NSL and GLAD, which has not been reported earlier. This process involves atomic layer deposition coating of silicon dioxide on polymeric substrates to enable self-assembly of nanospheres on these substrates, followed by GLAD on these self-assembled nanospheres. We demonstrated the detection of the pesticide Phosmet and the biomarker dipicolinic acid using flexible NSL-GLAD chips.