| The most significant obstacles to miniaturization of mobile robots down to micron scale are the miniaturization of on-hoard actuators and power sources required for mobility. To address these problems for swimming micro-robots, we propose interfacing live microorganisms (i.e. bacteria) with synthetic microfabricated robot body, with the ultimate goal of using bacteria for actuation, control, and sensing; and simple nutrients, such as glucose, for powering. By studying the hydrodynamics of bacterial flagellar motion, a design methodology for flagellar propulsion of swimming micro-robots is developed and key issues such as the effect of separation distance of neighboring flagella and the proximity of boundaries are experimentally studied. Propulsion of synthetic micro-spheres by bacteria is successfully demonstrated and critically analyzed. To achieve greater efficiency and motion directionality, a bullet-shaped polymeric body is microfabricated and a surfactant-based patterning technique is devised to limit the adhesion of bacteria to the flat end of the polymeric body. A chemical switching scheme is developed and successfully implemented to achieve repeatable on/off motion control of bacterial flagellar motors. Additionally, an on-board chemical release module is proposed and its feasibility is analyzed using a numerical mass-transfer model. Future applications of hybrid swimming micro-robots include early diagnosis and localized treatment of diseases. Potential target regions to use these robots include eyeball cavity, cerebrospinal fluid, and the urinary system. |
