title: All-optical control of microfluidic components using form birefringence.
abstract: The reflection and refraction of light at a dielectric interface gives rise to forces due to changes in the photon momentum. At the microscopic level, these forces are sufficient to trap and rotate microscopic objects. Such forces may have a profound impact in the emergent area of microfluidics, where there is the desire to process minimal amounts of analyte. This places stringent criteria on the ability to pump, move and mix small volumes of fluid, which will require the use of micro-components and their controlled actuation. We demonstrate the modelling, fabrication and rotation of microgears based on the principle of form birefringence. Using a geometric anisotropy (a one-dimensional photonic crystal etched into the microgear), we can fabricate microgears of known birefringence, which may be readily rotated by manipulating the input polarization in a standard optical trap. This methodology offers a new and powerful mechanism for generating a wide range of microfabricated machines, such as micropumps, that may be driven by purely optical control.
authors.affiliation: School of Physics and Astronomy, St Andrews University, St Andrews, Fife, KY16 9SS, UK. sln2@st-and.ac.uk
authors.forename: Steven L
authors.initials: SL
authors.lastname: Neale
authors.forename: Michael P
authors.initials: MP
authors.lastname: MacDonald
authors.forename: Kishan
authors.initials: K
authors.lastname: Dholakia
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Krauss
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry* / Q000528:radiation effects; D001718:Birefringence; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D008846:Micromanipulation / Q000295:instrumentation* / Q000379:methods; D020409:Molecular Motor Proteins / Q000737:chemistry*; D055095:Optics and Photonics / Q000295:instrumentation*; D012399:Rotation
chemical_list: D001672:Biocompatible Materials; D020409:Molecular Motor Proteins