Improvement of motility of bacterium-driven microobject fabricated by optical tweezers

Micro/nano robots have been actively studied to lead the developments of the novel technologies, such as drug delivery systems (DDS) and micro/nano surgery inside human body. Recently, the micro living organisms, especially flagellated bacteria, have been used as the driving forces for the microobjects. To achieve the more precise control of the bacteria-driven microobjects, we previously developed the method to assemble single bacterium onto a microobject using optical tweezers, unlike the conventional random and mass attachment. The assembly of the single bacterium onto a 3 μm microbead using optical tweezers was experimentally demonstrated. In this paper, we improve the motility of the bacterium-driven microobject by attaching multiple cells at the single point on the microobject. The motilities of the bacterium-driven microobject and the multi-bacteria-driven microobject are evaluated by the moving velocities. The two-bacteria-driven microbead shows ~2.3 time faster velocity than the velocity of the bacterium- driven microbead.