Roll-to-roll manufacturing of disposable surfaceenhanced Raman scattering (SERS) sensors on paper based substrates

We present two cost-effective routes for roll-to-roll (R2R) manufacturing of silver nanoparticle based surface-enhanced Raman scattering (SERS) active substrates on paper utilizing either inkjet printing or liquid flame spray (LFS) nanoparticle deposition. Paper is cost-effective, renewable, recyclable, and biodegradable that can easily be disposed after the SERS analysis. Paper based substrates can have a strong luminescence that can overshadow the rather weak SERS signal. Two solutions are presented here that solve the luminescence issue of the base paper substrate. A full silver coverage by inkjet printing or alternatively a simple flexography carbon coating can suppress the background luminescence allowing a reliable SERS characterization. The detection limit of the sample analyte crystal violet was 100 nM corresponding to 100 fmol in a 1 µl sample volume. These approaches can provide a cost-effective route towards disposable, point-of-care SERS active substrates.