Conclusions and Outlook - Towards Autonomous Soft Matter Systems - page 116

of the mechanism of Ca 2 + triggering of synaptic vesicle fusion. We were able to
unravel the electrostatic interactions that occur between the charged lipids and the
proteins that mediate the fusion process.Whilewewere able to reproduce, in vitro, the
massive increase of membrane fusion triggered by Ca 2 + , as seen in vivo, some of the
conditions we used in order to achieve it were not completely physiological. However
it is easily conceivable that many different factors of physiological environment can
lead to a similar condition as we used in the experiments. Thus, the mechanism of the
Ca 2 + triggering could be a basic mechanism at the heart of biological vesicle fusion
with minor variations in the conditions leading to it. Future experiments will help to
unravel both such conditions and if the mechanism we uncovered here is indeed as
basic as it promises to be.
Fundamental understanding, the tools and techniques that enable it and the appli-
cations that result from it all go hand in hand. In Chap. 4 we developed a technique
for the direct imaging of lipid bilayers with wide ranging implications. The work
demonstrated a first step towards imaging lipid bilayers reconstituted in microflu-
idic channels. The wide applicability of the techniques of microfluidics in a variety
of interdisciplinary studies makes such an investigation vital. Our data showed that
it was possible to image an unthinned lipid membrane with resolutions down to
∼ 200nm in one dimension. The technique is particularly promising as it did not

cause any photo-damage, typical of many X-ray studies, to the bilayer samples that
were studied. The model that we used to extract the structural information from the
data is a simple and scalable one, such that improvements of resolution up to an
order of magnitude might be possible with suitable adjustments to both model and
experiment.
In the second part of this work, we investigated artificial active matter—emulsion
droplets dissipating chemical energy. The well known and studied Belousov-
Zhabotinsky chemical reaction was run in micro-droplets, thus creating populations
of chemical micro-oscillator droplets as discussed in Chap. 5 . Qualitatively new phe-
nomena emerged due to the interplay between the droplet network topologies and
type of coupling between the oscillators. In combination with the results presented
in Chap. 2 , these open up the possibilities to construct self-organizing dynamic soft
matter systems. These systems are particularly well suited as a table top system for
the study of many open questions in non-equilibrium science. Effects such as quorum
sensing are widely seen in natural settings and have recently been reported in artificial
chemical oscillators. However, there is no deep understanding of such phenomena,
particularly due to the difficulty in resolution of a single, isolated oscillator where
very large populations are present. The results that we have presented in Chap. 5
might pave the way for detailed investigations.
In the light of understanding the emergence of collective states and phase tran-
sitions in non-equilibrium settings, self propelled particles are rapidly gaining
popularity as an elegant model system. In this context, we introduced an artifi-
cial micro-swimmer in Chap. 6 . We studied the mechanism driving its motion and
characterised its velocity and showed that it mimics an idealised model of natural
microscale swimming. Unlike many other artificial self propelled objects, these can
be created easily and in large quantities with identical properties, without the many