White-light-driven plasmonic nanoparticle printing for opto-thermal manipulation and SERS application

The optical printing of nanoparticles from a colloidal solution is a simple and flexible approach and is currently being explored for printing plasmonic particles at desired locations. However, the practical application of such printed patterns is limited as it relies on focused laser beams for the bubble-assisted or direct printing of the nanoparticles. Here, we demonstrate the white-light-assisted printing of plasmonic nanoparticles and the utilization of the same for optothermally trapping the objects at desired locations via selective optical radiation exposure to a multi-patterned substrate. By combining the selective exposure and the optothermal force, the tweezing of the trapped object along the pre-defined paths is also illustrated. The surface-enhanced Raman spectroscopy studies carried out on the printed plasmonic patterns reveal that the printing time scale determines the Raman signal enhancement, and the optimized printed patterns provide a limit of detection of 62 pM for the probe molecule, crystal violet.