Dielectrophoretic positioning of single nanoparticles on atomic force microscope tips for tip-enhanced Raman spectroscopy
in: Electrophoresis (2015)
Tip- enhanced Raman spectroscopy ( TERS), a combination of Raman spectroscopy and scanning probe microscopy , is a powerful technique to detect the vibrational fingerprint of molecules at the nanometer scale . A metal nanoparticle at the apex of an AFM tip leads to a large enhancement of the electromagnetic field when illuminated with an appropriate wavelength , resulting in an increase d Raman signal. A controlled positioning of individual nanoparticles at the tip would improve the reproducibility of the probes, but is quite demanding due to usually serial and labor - intensive approaches. In contrast to other commonly used submicron manipulation techniques, dielectrophoresis (DEP) allows a parallel and scalable production, and provides a novel approach towards reproducible and at the same time affordable TERS tips. We demonstrate the successful positioning of an individual plasmonic nanoparticle on a commercial AFM tip by DEP followed by experimental proof of the Raman signal enhancing capabilities of such tips.