title: Plasmonic nanotweezers: strong influence of adhesion layer and nanostructure orientation on trapping performance.
abstract: Using Au bowtie nanoantennas arrays (BNAs), we demonstrate that the performance and capability of plasmonic nanotweezers is strongly influenced by both the material comprising the thin adhesion layer used to fix Au to a glass substrate and the nanostructure orientation with respect to incident illumination. We find that a Ti adhesion layer provides up to 30% larger trap stiffness and efficiency compared to a Cr layer of equal thickness. Orientation causes the BNAs to operate as either (1) a 2D optical trap capable of efficient trapping and manipulation of particles as small as 300 nm in diameter, or (2) a quasi-3D trap, with the additional capacity for size-dependent particle sorting utilizing axial Rayleigh-Bénard convection currents caused by heat generation. We show that heat generation is not necessarily deleterious to plasmonic nanotweezers and achieve dexterous manipulation of nanoparticles with non-resonant illumination of BNAs.
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Roxworthy
authors.forename: Kimani C
authors.initials: KC
authors.lastname: Toussaint
mesh_terms: D000268:Adhesiveness; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D008027:Light; D008846:Micromanipulation / Q000295:instrumentation*; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation*; D052898:Optical Tweezers; D013314:Stress, Mechanical; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D006046:Gold