Authors: E.P. Furlani, A. Baev, P.N. Prasad
Affilation: University at Buffalo, United States
Pages: 1 - 4
Keywords: nanotrapping, sub-wavelength particle trapping, nanophotonics, nanomanipulation, dipolar force
The interest in optical particle manipulation has grown steadily in recent years especially for applications in the biological sciences where the manipulated objects include cells, organelles, and larger molecules. While micron and sub-micron bioparticles can be manipulated using conventional optical tweezers, the resolution of this approach is diffraction-limited (~250 nm) by the optics used to produce the spatial gradient of the EM field. In this presentation we discuss a novel method for nanoscale trapping wherein nanoparticles are manipulated using the enhanced near-field gradients that exist around sub-wavelength metallic nanostructures. Optically-induced nanomanipulation holds potential for a number of diverse applications including nanoparticle chemistry, nanorheology, nanoscale bioseparation and ultra-sensitive biosensing. We present an analysis of optical nanotrapping with reference to specific bioapplications. We analyze the dipolar force on sub-wavelength nanoparticles in proximity to illuminated metallic (gold) nanopillars. We compute the force using 3D time-harmonic electromagnetic finite element analysis (FEA), and use a Drude model for the dielectric permittivity of the gold nanopillars. We study the dipolar trapping force as a function of key variables including the polarization of the incident field, the dimensions of the nanopillars, and the dimensions and dielectric strength of the nanoparticles. We examine regions of particle trapping, and discuss particle motion taking into account optical and fluidic forces. The analysis we present provides insight into optical trapping physics and enables the design of novel nanotrapping systems for bioapplications. We discuss specific bioapplications and present different nanotrapping designs.