title: Custom-Made Microspheres for Optical Tweezers.
abstract: Due to their high position and force sensitivity and the ability to remotely apply forces and torques, optical tweezers are widely used in diverse fields, such as biology, material science, and physics. Often, small dielectric particles are trapped and used as probes, which for experimental convenience are mostly spherical and composed of silica or polystyrene. The optical properties of these materials together with the microsphere size determine the trapping efficiency, and the position and force resolution. However, using only a single, homogeneous, isotropic, and unstructured material limits the range of trapping properties and thereby the applications of optical tweezers. Here, we show how custom-made microspheres composed of coated high-refractive-index materials-titania and nanodiamonds-and birefringent, liquid crystals extend the range and combination of desired trapping properties. These custom-made microspheres either enable the generation of high forces, a high force or time resolution, or the applications of torques. Custom-made probes expand the range of possible experiments and approaches broadening the scope and applicability of optical tweezers.
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
authors.forename: Anita
authors.initials: A
authors.lastname: Jannasch
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
authors.forename: Mohammad K
authors.initials: MK
authors.lastname: Abdosamadi
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
authors.forename: Avin
authors.initials: A
authors.lastname: Ramaiya
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
authors.forename: Suman
authors.initials: S
authors.lastname: De
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
authors.forename: Valentina
authors.initials: V
authors.lastname: Ferro
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
authors.forename: Aaron
authors.initials: A
authors.lastname: Sonnberger
authors.affiliation: Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany. Erik.Schaeffer@uni-tuebingen.de.
authors.forename: Erik
authors.initials: E
authors.lastname: Schäffer
mesh_terms: D008863:Microspheres; D053758:Nanoparticles / Q000737:chemistry; D052898:Optical Tweezers; D055095:Optics and Photonics / Q000379:methods; D012822:Silicon Dioxide / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium
keywords: Angular trapping; Anti-reflection coating; Core–shell particles; Liquid crystalline birefringent particles; MCM-41; Microspheres; Nanodiamonds; Nanonewton; Optical torque; Optical tweezers; Rotation; TEOS; Titania