Fabrication Of Rotational Magnetic Field-Based And Simple Shaped Microswimmer And Their Swimming Performance

Microrobot/microswimmer has been widely investigated within this decade because of its great potential to be used in drug delivery,non-invasive surgery,microano-manipulation and bio-sensing.In tradition,helical structure was widely adopted to generate non-reciprocal motion to overcome the drag force of low Reynolds number environment under the control of rotational magnetic field.In recent years,the rotational magnetic field controlled achiral microswimmer attracted significant attention due to its simple fabrication method,considerable swimming performance and steerability.In this thesis,we combined photolithography and e-beam evaporation to fabricate two-dimensional achiral microswimmer and introduced curvature into the microswimmer.We compared the swimming performance of curvature-imparted crescent-shaped microswimmer with L-shaped microswimmer.We first compared the forward swimming speed when the microswimmer was in the bulk fluid and near the boundary in order to valid its consistency.Then,we investigated both the forward swimming velocity and drift velocity of those crescent-shaped and L-shaped microswimmers.In the meantime,we proposed a zigzag trajectory control strategy to indirectly eliminate the defect of drift motion by taking the advantage of that the achiral microswimmers would not change their swimming direction when the rotational direction of the rotational magnetic field was reversed.Last,we conducted experiment to study the flow field generated by the rotating L-shaped microswimmer under rotational magnetic field using ?-PIV technology.By studying the achiral microswimmers,we obtained the following results:(1)with the same critical size,the introduce of curvature to crescent-shaped microswimmer significantly improved the forward swimming velocity when comparing to the L-shaped microswimmer and the forward swimming velocity decreased with the increase of inner diameter of the crescent-shaped microswimmer.(2)We proposed a zigzag-trajectory control strategy that can be used to indirectly eliminate the defect of drift motion.(3)We firstly conducted experiment method to investigate the hydrodynamics of a moving achiral microswimmer.In this paper,we studied the shape and structure design of achiral microswimmer by introducing curvature structure to improve the swimming performance of achiral microswimmer,which will provide important significance for future design of achiral microswimmer.Meanwhile,we firstly conducted experiment on the hydrodynamics of achiral microswimmer,which is important for the investigation of achiral microswimmer while providing both theoretical and experimental fundamental studies.