title: Individual Template-Stripped Conductive Gold Pyramids for Tip-Enhanced Dielectrophoresis.
abstract: Gradient fields of optical, magnetic, or electrical origin are widely used for the manipulation of micro- and nanoscale objects. Among various device geometries to generate gradient forces, sharp metallic tips are one of the most effective. Surface roughness and asperities present on traditionally produced tips reduce trapping efficiencies and limit plasmonic applications. Template-stripped, noble metal surfaces and structures have sub-nm roughness and can overcome these limits. We have developed a process using a mix of conductive and dielectric epoxies to mount template-stripped gold pyramids on tungsten wires that can be integrated with a movable stage. When coupled with a transparent indium tin oxide (ITO) electrode, the conductive pyramidal tip functions as a movable three-dimensional dielectrophoretic trap which can be used to manipulate submicrometer-scale particles. We experimentally demonstrate the electrically conductive functionality of the pyramidal tip by dielectrophoretic manipulation of fluorescent beads and concentration of single-walled carbon nanotubes, detected with fluorescent microscopy and Raman spectroscopy.
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Jincy
authors.initials: J
authors.lastname: Jose
authors.affiliation: Optical Materials Engineering Laboratory, ETH Zürich , 8092 Zürich, Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kress
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States ; Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Avijit
authors.initials: A
authors.lastname: Barik
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Otto
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Jonah
authors.initials: J
authors.lastname: Shaver
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Johnson
authors.affiliation: Photonics Laboratory, ETH Zürich , 8093 Zürich, Switzerland.
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Lapin
authors.affiliation: Photonics Laboratory, ETH Zürich , 8093 Zürich, Switzerland.
authors.forename: Palash
authors.initials: P
authors.lastname: Bharadwaj
authors.affiliation: Photonics Laboratory, ETH Zürich , 8093 Zürich, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Novotny
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States ; Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Oh
keywords: dielectrophoresis; gradient force; particle trapping; plasmonics; template stripping