We study the motion of a Janus particle in an inhomogeneous external temperature field generated by an optically heated gold nanoparticle. The Janus particle consists of a polystyrene particle covered on one hemisphere with a 50 nm gold film. The Janus particle is held in the vicinity of the immobilized gold nanoparticle by photon nudging, which actively propels the Janus particle towards a target. Close to the heat source, the propulsion is switched off. We find an angle dependent repulsion of the particle from the heat source. Further, an angular velocity of the Janus particle is measured, which results in an active polarization of the Janus particle in the temperature field.
Andreas P. Bregulla and Frank Cichos, "Polarization of thermophoretic swimmers in external temperature fields," Proc. SPIE 9922, Optical Trapping and Optical Micromanipulation XIII, 99221L (Presented at SPIE Nanoscience + Engineering: August 31, 2016; Published: 15 November 2016); https://doi.org/10.1117/12.2239482.
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