title: Angular trapping of anisometric nano-objects in a fluid.
abstract: We demonstrate the ability to trap, levitate, and orient single anisometric nanoscale objects with high angular precision in a fluid. An electrostatic fluidic trap confines a spherical object at a spatial location defined by the minimum of the electrostatic system free energy. For an anisometric object and a potential well lacking angular symmetry, the system free energy can further strongly depend on the object's orientation in the trap. Engineering the morphology of the trap thus enables precise spatial and angular confinement of a single levitating nano-object, and the process can be massively parallelized. Since the physics of the trap depends strongly on the surface charge of the object, the method is insensitive to the object's dielectric function. Furthermore, levitation of the assembled objects renders them amenable to individual manipulation using externally applied optical, electrical, or hydrodynamic fields, raising prospects for reconfigurable chip-based nano-object assemblies.
authors.affiliation: CNISM - Department of Physics, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milan, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Celebrano
authors.forename: Christina
authors.initials: C
authors.lastname: Rosman
authors.forename: Carsten
authors.initials: C
authors.lastname: Sönnichsen
authors.forename: Madhavi
authors.initials: M
authors.lastname: Krishnan
mesh_terms: D016880:Anisotropy; D004247:DNA / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D057446:Hydrodynamics; D007700:Kinetics; D046911:Macromolecular Substances; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D055095:Optics and Photonics; D010316:Particle Size; D010825:Physics / Q000379:methods; D012542:Scattering, Radiation; D012834:Silver / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D012834:Silver; D004247:DNA