| Recently, there are growing interests in microrobotics to accomplish micro scale tasks such as single cell manipulation, cell therapy and drug delivery. Due to the need for complicated fabrication techniques and the absence of sensing elements of artificial microrobots, biological microrobots which utilize motile microorganisms as a platform have been highlighted as an alternative. In this thesis, control of the Tetrahymena pyriformis ( T. pyriformis), a biological cellular microrobot using galvanotaxis, phototaxis, and magnetotaxis is demonstrated. Electrical stimulation, in the form of a direct current (DC) electric field through the containing fluid, causes a change in swimming direction towards the cathode. Photo-stimulation, by high intensity broadband light, results in a rotational motion of the cells. Magnetotaxis is the ability to sense magnetic fields which allows a cell to coordinate its motion in response. Magnetotaxis is artificially implemented to T. pyriformis by internalizing magnetic nano-particles into the cell body in order to develop the robustly controllable biological microrobot. Since the artificial control modules are combined into the biological system, the motion of artificial magnetotactic T. pyriformis is finely controllable. Using external time-varying magnetic fields, the swimming direction of artificial magnetotactic T. pyriformis can be controlled while the propulsive swimming force is exerted by the endogenous motility of the cell. In this thesis, the fabrication and control methods of artificial magnetotactic T. pyriformis have been introduced and demonstrated. In order to develop a kinematic model, the magnetic properties of the developed microrobot are characterized and proved experimentally. In the results, real-time autonomous control is demonstrated using an integrated system with feedback control schemes and feasible path planning algorithms. In addition, three-dimensional control is developed and demonstrated as well. |
