Biomimetic propulsion for a swimming surgical micro-robot

A surgical micro-robot that swims inside the human ureter is proposed to provide a novel and minimally invasive method of kidney stone destruction. Inspired by the swimming mechanisms of bacteria such as E. coli, the robot utilizes biomimetic synthetic flagella composed of multiwalled carbon nanotubes that are driven into a rotating helical shape by a micro motor. Design aspects are discussed with the focus on locomotion. The performance of the propulsion mechanism is determined through simultaneous modeling of the viscous drag on the filaments and the stress strain behavior of the nanotubes. The effects of the synthetic flagellum geometry and frequency of rotation on efficiency and swimming speed are explored. With 1 nW of power, utilizing 100 μm-long filaments, swimming speeds approaching 1 mm/s are shown to be possible for a realistic design. The proposed new robot would revolutionize kidney stone destruction if implemented, yet the design of the robot and the propulsion analysis are applicable to many other possible surgical procedures.