Chemistry Reference
In-Depth Information
Fig. 7.18
Rheological measurements on
Left
Bacterial suspensions which are pusher type swim-
mers [
31
]and
Right
Chlamydomonas suspensions which are puller type swimmers [
32
]
already underway, we anticipate that many more exciting investigations are possible
by simple extensions of the current system.
The rheological properties of suspensions of microswimmers are still very unclear.
AsshowninFig.
7.18
, recent measurements on bacterial suspensions revealed an
effective decrease in the viscosity of the medium with increasing swimmer density
in the dilute regime (left panel) [
31
] while similar experiments with chlamydomonas
suspensions revealed an increase at similar densities (right panel) [
32
]. The bacterium
is a pusher type of swimmer, while chlamydomonas pull themselves. However it is
not clear how such a distinction might explain the findings or even if this distinction
alone is sufficient to account for the different behaviours. The droplet squirmers
investigated here might help in addressing some of these issues. Since considerable
work has been done on the rheology of emulsions, such principles and experiments
could be extended to study the rheology of the active emulsions presented here.
Further, there has been growing interest in the motion of microscale swimmers
through complex networks such as that of disease causing pathogens wading throu-
gh the complex blood stream network [
33
]. This clearly has implications for disease
Fig. 7.19
Droplet swimmers
on 2-D lattice and random
network topologies.
White
spaces
represent 'channels',
black
regions are walls and the
red circles
indicate swimmers
