Self-propelling particles (SPP)

Collective motion is one of the conspicuous features of life. Non-living systems, such as nematic fluids, shaken metallic rods, nano-swimmers, simple robots, and boats, are a few good examples. Living system, such as fish schools, bird flocks, bacteria swarms, and traffic jam, are other good examples.

SPP1

Our self-propelling particle is bacteria. The reason that we choose bacteria is because it possess molecular motors which are able to perform highly efficient flagellum rotation even under low Reynolds number condition.

SPP2

Wild type vibrio alginolyticus (VIO5) is a bacterium strain which exhibit highest swimming rate (51μm/s) ever recorded. The bacterium is propelled by the rotational motion of its single polar flagellum with rotation rate as high as several hundred hertz. The rotational rate can be tuned by sodium concentration in TMN medium (50mM Tris–HCl(pH 7.5), 5mM MgCl2, 5mM glucose, 300mM NaCl+KCl). NMB136 is another Vibrio alginolyticus bacteria strain. The swimming modes of VIO5 are two folds, forward and backward motion, switched by large angle flicking of flagellum. On the other hand, NMB136 only perform forward swimming motion with counter-clockwise flagellum rotation.

SPP3

We achieve high coverage carpet formation by coating poly-lysine on the glass surface in the ~100μm high micro-fluidic channel.

SPP4