Efficient Optical Manipulation of Janus Particles by Optical Nanofibers

Abstract

Small composite objects, known as Janus particles, drive sustained scientific interest primarily targeted at biomedical applications, where such objects act as micro- or nanoscale actuators, carriers, or imaging agents. The major practical challenge is to develop effective methods for manipulation of Janus particles. The available long-range methods mostly rely on chemical reactions or thermal gradients, therefore having mediocre precision and strong dependency on the content and properties of the carrier fluid. To tackle these limitations, we propose the manipulation of Janus particles (here, silica microspheres half-coated with gold) by optical forces in the evanescent field of an optical nanofiber. We find that Janus particles exhibit stronger transverse localization and faster propulsion compared to all-dielectric particles of the same size. The propulsion speed recorded for a 3-$\mu$m particle with a 20-nm-thick gold cap averages at 2~$\mu$m/s per 1~mW of optical power, reaching 133 body length/s at 200~mW going through the nanofiber.

arXiv comment26 pages, 6 figures

References in corpus (11)

• Microswimmers in Patterned Environments
• Active Brownian Motion Tunable by Light
• Phototaxis of synthetic microswimmers in optical landscapes
• Self-propelled Janus particles in a ratchet: Numerical simulations
• Optical Micro- and Nanofiber Pulling Rig
• Flow pattern in the vicinity of self-propelling hot Janus particles
• Polarization of active Janus particles
• Self-diffusiophoresis of Janus particles in near-critical mixtures
• Selective particle trapping and optical binding in the evanescent field of an optical nanofiber
• Complete polarization control for a nanofiber waveguide using directional coupling
• Optical transport of sub-micron lipid vesicles along an optical nanofibre