Mite Mijalkov obtains his Master's Degree

December 19th, 2014

Mite Mijalkov obtains his Master's Degree

Mite Mijalkov will defend his MSc thesis on December 19, 2014.

The title of his Master's thesis is: Sorting of chiral microswimmers and robotic swarms. This work is related to the field of the motion of active particles, and the study of collective behaviours of a systems composed of many active elements.

More in details: microscopic swimmers, for example chemotactic bacteria and cells, are capable
of directed motion by exerting a force on their environment. In some cases, including bacteria
and spermatozoa swimming near boundaries, or many asymmetrical artificial microswimmers,
the driving force and propulsion direction are misaligned. In those situations a torque acting on
the microswimmers arises, resulting in motion with a well-defined chirality which is circular in
two dimensions and helicoidal in three dimensions.

In this presentation, it is shown with numerical simulations in two dimensions, how the chirality
of the circular motion can couple to chiral features present in the microswimmer environment.
It is shown that by employing static chiral pattern of elliptical obstacles in their environment,
microswimmers can be separated on the basis of their motion parameters. In particular, levogyre
and dextrogyre microswimmers as small as 50 nm can be separated and selectively trapped in
chiral flowers of ellipses. Patterned microchannels can be used as funnels to rectify the microswimmer
motion, as sorters to separate microswimmers based on their linear and angular velocities, and
as sieves to trap microswimmers with specific parameters. It is also also demonstrated that these
results can be extended to helicoidal motion in three dimensions.

Finally, it is shown experimentally that in a swarm of mini robots, where each robot is capable of
emitting a light gradient around itself, depending on the sensorial delay the robots tend either to
move away from each other or to form a swarm that moves as a single entity.

The thesis committee is composed by Asst. Prof. Dr. Giovanni Volpe (Bilkent University),
Assoc. Prof. Dr. Hande Toffoli (METU) and Asst. Prof. Dr. Miguel Navascuès (Bilkent University).