Low-cost replication of plasmonic gold nanomushroom arrays for transmission-mode and multichannel biosensing

A plasmonic gold nanomushroom array (GNMA), whose figure of merit (FOM) is close to the theoretically predicted upper limit for standard propagating surface plasmon resonance (PSPR) sensors, made the biosensing performance of this type of LSPR sensor comparable to that of commercial PSPR sensors. However, for commercial implementation of GNMA sensors, a low-cost fabrication method and a simple optical measurement scheme are both urgently required. Herein, we introduce elastic soft lithography to replicate GNMAs with uniform shapes and sizes. This approach is low-cost, facile and reproducible, and might be suitable for industrial production of a mushroom nanopillar array whose tops are larger than their middles. The as-obtained GNMAs consisting of a transparent substrate were applied to convenient normal transmission measurements, and showed excellent refractive index sensitivity and FOM value. Notably, four medical analytes were simultaneously detected on a microarray chip integrated with a GNMA sensing component, suggesting that the GNMA sensing substrate is a promising candidate for high-throughput monitoring of multiple analytes.