Design, characterization, visualization and navigation of swimming micro robots in channels

Official URL: http://risc01.sabanciuniv.edu/record=b1534411 (Table of Contents)

Recent advances in micro- and nano-technology and manufacturing systems enabled the development of small (1μm – 1 mm in length) robots that can travel inside channels of the body such as veins, arteries, similar channels of the central nervous system and other conduits in the body, by means of external magnetic fields. Bioinspired micro robots are promising tools for minimally invasive surgery, diagnosis, targeted drug delivery and material removal inside the human body. The motion of micro swimmers interacting with flow inside channels needs to be well understood in order to design and navigate micro robots for medical applications. This thesis emphasizes the in-channel swimming characteristics of robots with helical tails at low Reynolds number environment. Effects of swimming parameters, such as helical pitch, helical radius and the frequency of rotations as well as the effect of the radial position of the swimmer on swimming of the helical structures inside channels are analyzed by means of experiments and computational fluid dynamics (CFD) models using swimmers at different sizes. Micro particle image velocimetry (micro-PIV) experiments are performed to visualize the flow field in the cylindrical channel while micro robot has different angular velocities. The effects of solid plane boundaries on the motion of the micro swimmers are studied by experiments and modeling studies using micro robots placed inside rectangular channels. Controlled navigation of micro robots inside fluid-filled channel networks is performed using two different motion mechanism that are used for forward and lateral motion, and using the strength, direction and frequency of the externally applied magnetic field as control inputs. Lastly, position of the magnetic swimmers is detected using Hall-effect sensors by measuring the magnetic field strength.