On the cover of Soft Matter


July 19, 2013

Soft Matter cover for M. Mijalkov and G. Volpe's article

M. Mijalkov and G. Volpe's article, "Sorting of Chiral Microswimmers",
was featured on the cover of Soft Matter, July 28 2013, Issue 28.

The article investigates the behaviour of asymmetric microswimmers, e.g.,
bacteria, spermatozoa and many artificial active colloidal particles that
have a non-symmetric shape and are able to self-propel themselves.

Such microscopic asymmetric swimmers are characterized by a circular
motion (in two dimensions) and a helicoidal motion (in three dimensions)
with a well-defined chirality, because a torque is also present.

In the article M. Mijalkov and G. Volpe demonstrate with numerical
simulations in two dimensions how the chirality of circular motion couples
to chiral features present in the microswimmer environment.

It is shown how 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.

They also demonstrate that these results can be extended to helicoidal
motion in three dimensions.