Multiflagella artificial bacteria for robust microfluidic propulsion and multimodal micromanipulation

Artificial micro/nanoswimmers mimicking biological microorganisms have drawn much interest toward biological or biomedical applications thus rapidly growing over the past few years from various approaches. Various morphologies and propulsion methods have been proposed to overcome the limited propulsion dynamics at a low Reynolds number liquid environment where such swimmers suffer from increased viscous drags. Cork-screw motion of single flagellum has mostly been studied so far to mimic bacterial propulsion. Although their propulsion efficiency is improved, their integration, propulsion and manipulation inside completely closed microfluidic channel are not trivial due to high surface effect, low propulsion dynamics and unstable motion control under flux. Therefore it is required to further enhance their propulsion robustness and stability of motion control. In this paper, we propose multiflagella artificial bacteria demonstrating enhanced characteristics of propulsion dynamics, controllability, robustness, manipulation functionality, thus proving their capability as wireless micromanipulators inside microfluidic channels thanks to their surface based motions such as tumbling or rolling. We show the enhanced user controllability, frequency triggered multimodal propulsion characteristics with rolling/tumbling and multimodal manipulation functions of trapping/assembly/pushing. Moreover the successfully demonstrated microfluidic channel navigation capability under both static and dynamic pressure simulates the feasibility toward in-vivo biomedical applications such as targeted drug delivery or other micromanipulation tasks inside blood vessels.