Swimming of onboard-powered autonomous robots in viscous fluid filled channels

Microrobots can make a great impact in medical applications such as minimally-invasive surgery, screening and diagnosis of diseases, targeted therapy and drug delivery. Smallsized bio-inspired robots can mimic flagellar propulsion mechanisms of microorganisms for actuation in microfluidic environments, which are dominated by viscous forces. Microorganisms propel themselves by means of the motion of their flagella such as rotation of rigid helices or travelling planar waves on flexible tails similar to whipping motion. Here, we present characterization of swimming of onboard-powered autonomous robots inside cylindrical tubes. Robots consist of two links, head and tail, connected with a revolute joint. Rigid helical tails of the swimmer robots are made of steel wires with 12 different configurations of helical radius and pitch. From experiments forward linear velocity of robots and angular velocities of the links are measured, and compared with the mathematical model, which is based on the resistive force theory. Results indicate that the motion of the swimmer inside channels can be predicted by means of the resistive force theory reasonably well.