Direct printing of gold nanospheres from colloidal solutions by pyro-electrohydrodynamic jet allows hypersensitive SERS sensing

Pyro-electrohydrodynamic jet printing (p-jet) has been used to fabricate a nanostructured plasmonic sensor for SERS spectroscopy. The p-jet approach allowed us to have an assembly of nanoparticles with suitable geometry and size, which resulted in a sensing surface with intense SERS activity and a rather homogeneous response. Raman imaging measurements highlighted strong Enhancement Factors across the sensing area, exceeding those of the pristine colloidal solution by almost two orders of magnitude. The intense plasmonic effect was further demonstrated by the spectroscopic recognition of a metal-catalyzed dimerization process triggered to completeness at the metal surface. The results presented herein demonstrate the usefulness of the proposed SERS sensor for hypersensitive molecular analysis.