Chemistry Reference
In-Depth Information
Fig. 5.13
Antiphase pattern in a 1 dimensional oscillator network.
To p
Droplet oscillators in a
glass microcapillary. Each droplet pair is connected by bilayer membranes. The droplet diameter
is 100
ยต
.
Bottom
Time trace of the droplet oscillations shown for the three droplets in the center of
the top image. The
red
,
blue
and
green
traces correspond to the droplets marked as shown
As anticipated, the increase in the concentration of Malonic acid resulted in a non-
wave-like pattern as shown in Fig.
5.13
where every oscillator droplet is found to be
in strict anti-phase with its neighbour. This can be understood to be a complicated
interplay between the inhibitory and excitatory coupling. In fact it has been shown
that the anti-phase state is an attractor for inhibitory coupling [
6
,
7
]. However, in such
models of inhibitory coupling, the interdroplet distance is quite large as compared to
our experiments where the droplets are separated only by a nanometric membrane.
This illustrates that the membrane between the oscillator droplets play an important
role in preserving the individual properties of each oscillator. These studies though
only demonstrative, must be performed in greater detail in order to quantitate the
various synchronization patterns and their relation to the network topology. In par-
ticular, a knowledge of the permeability of the membrane to the various coupling
intermediates is crucial to have predictive control over the oscillator behaviour.
5.4 Summary and Outlook
Active emulsions, chemical micro-oscillator droplets as presented here, may provide
a crucial first step towards the realization of active soft matter which demonstrate
complex dynamic functions. The Belousov-Zhabotinsky reaction used here has been
studied as a paradigm system for the study of dynamical and pattern forming sys-
tems for many years. In the present setting of using it within microfluidic emul-
sion droplets, qualitatively new phenomena emerge due to the interplay between the
droplet network topologies and type of coupling between the oscillators. As we have
shown, bilayer membranes play a crucial role in the coupling and synchronization
