Efficient fabrication of highly sensitive AgNPs-drawing paper SERS substrates by robotic writing approach

Inspired by hand writing approach for preparing surface-enhanced Raman scattering (SERS) substrates, silver nanoparticles (AgNPs) decorated drawing paper substrates were prepared by robotic writing technique. The wettabilities and surface morphologies of the drawing paper before and after the deposition of AgNPs were characterized by contact angle analyzer and scanning electron microscope, respectively. Malachite green was employed as a probe molecule to evaluate the SERS activities of the AgNPs-drawing paper substrates. The AgNPs-drawing paper substrates exhibited extremely high sensitivity that the detection limit for malachite green was down to 10^-18 mol/L and the Raman enhancement factor was calculated to be 10¹⁵. The relative standard deviation (RSD) values of the Raman peaks intensities collected from twelve points on a single substrate and fifteen substrates were used to evaluate the uniformity and reproducibility of the AgNPs-drawing paper substrates. It was found that the substrates had good reproducibility and uniformity with RSD values of 7.29% and 9.70%, respectively. Furthermore, the prepared AgNPs-drawing paper substrates exhibited long-term stability among six months.