A Crystal-Clear Sers-Droplet with Evenly Distributed 3D Hot-Spots

In this work, a crystal-clear SERS-droplet is proposed, inside of which hot-spots are evenly distributed in three-dimension. Such a droplet is prepared by rolling an aqueous droplet on a superhydrophobic SERS substrate composed of carbon nanoparticles (CNPs) and their protecting nanolayer of Parylene C (PC). Such a CNP-PC stacked SERS substrate is fabricated simply by flame deposition of CNPs, chemical vapor deposition of a PC nanolayer, and noble-metal sputtering. Due to the three-dimensional (3D) distribution of hot-spots, such a SERS-droplet is about 18.5 times more sensitive than a similar SERS substrate involving only two-dimensional hot-spots, and achieves an enhancement factor as large as 6.6 ×10⁷. Besides, ascribe to even distribution of the hot-spots, the SERS-droplet has a relatively high repeatability.