Fig. 1
From: SERS discrimination of single DNA bases in single oligonucleotides by electro-plasmonic trapping
Electro-plasmonic trapping for single-molecule SERS. a Schematic of the flow-through setup that allows single gold nanourchin (AuNU) to flow through and be trapped under applied bias in a gold nanohole at plasmonic resonance upon the laser excitation at 785 nm. b The trapping due to a balance between the electrophoretic (FEP), electroosmotic (FEO), and optical (FOF) forces leads to a plasmonic hot spot between the AuNU tip and the nanohole sidewall that allows single-molecule SERS. c SEM image of the gold nanohole. The scale bar is 200 nm. d TEM image of the AuNU. The scale bar is 10 nm. e Simulated electromagnetic field intensity distributions of the AuNU coupled with the nanohole. The color bar represents the enhancement of the electromagnetic field intensity. f Magnified view of the intensity distribution of the electromagnetic field at one tip of the AuNU. The scale bar is 2 nm.
