Investigations of Flow and Particle Clustering Around Optically Trapped Rotating Nanorods

Abstract

The investigation and development of nanomachines is a topic that is widely researched, as it promises applications in fields like physics, biology or medicine. A recent development of this research are light-driven rotary motors, consisting of optically trapped gold nanorods. These rods are brought to rotate by the use of circularly polarized light, making use of their plasmonic characteristics. It is now of interest to better understand the effect that these nanorotors have on their environment. In this context, this work explores the clustering of fluorescent nanospheres around an optically trapped, rotating nanorod by the means of a combination of dark-field and fluorescence microscopy. The work also discusses an attempt to track particles in order to map the microfluidic flow around the trapped nanorod. By observing the changes in brightness that occur when a particle enters this cluster, it was possible to show that the rotation of a nanorod can induce and amplify the clustering of these particles around it. Furthermore, the results suggest that higher laser powers also support stronger clustering.