We achieved the following progress towards the objectives of the COCONUTE project:
a) We designed, built and optimized an optical set-up able to characterize accurately the thickness of micrometric thin viscous liquid coatings deposited by dip-coating on a flat plate. The technique we developed is based on laser-induced fluorescence (LIF) and can be applied to films as thin as < 10 m, the characteristic size of eukaryotic cells. In the future, this technique may be exploited for the characterization of complex coatings (e.g. made of viscoelastic liquids) relevant to tissue engineering applications.
b) We developed a theory to describe the double coated film entrained on a flat plate pulled from a bath made of two immiscible liquid layers (e.g. oil on top of water). The model allows to compute the thicknesses of the coated films and predicts that one of them is always much thinner than the other. The results of our theoretical and numerical study were published in 2021 in the leading journal of our field, the Journal of Fluid Mechanics. They were also presented in two international and one national conferences.
c) We discovered a way to generate in a very controlled fashion floating drops (called liquid lenses) with volumes in the microliter scale, relevant to tissue engineering applications. By varying experimentally the injection flow rate and viscosity of the liquid forming the drops, we found scaling laws describing how the drop volume and their generation rate depend on these control parameters. Moreover, we have rationalized these experimental findings with a simple mathematical theory. We are currently preparing two scientific articles describing two different aspects of the problem.
d) We designed and optimized an experimental setup to produce an inertia-driven flow of a viscous fluid in a porous fiber bundle, by the means of short, well-controlled impacts. In our experiments we varied both the intensity of the impact and the viscosity of the liquids to determine in which region of the parameter space this inertia-driven transport mechanism could be achieved. The experimental data was rationalized using order-of-magnitude analyses. These results have been presented in an international conference in 2022.
During the project, we also organized three events to disseminate our results to less specialized audiences. Two of these events were scientific workshops targeting technical but broad audiences (soft matter scientists in general or even researchers from other scientific areas). Another event was addressed to the general public, in the context of the Madrid Science Week in 2021.
