Coarse-grained model for the simulation of "active drops"

Micro-droplets of fluid can behave in peculiarly “active” ways if subject to the action of external perturbations. The many possible applications and interesting properties they can express experimentally makes them the object of several studies. Water micro-droplets motion on small devices can be used for generating electrical currents and power simple electronic devices. Their motion can be also controlled for the creation of micro-reactors, micro-pumps and micro-fluidic devices. High interest is focused on the possibility to use them for mimicking the behavior of living systems, using a variety of experimental and computational set ups. My work was concerned with the development of a theoretical coarse-grained model for the simulation of some peculiar behaviour of active droplets. The model considers the mechanical response of the set of particles, here called beads, that interacts by proper combinations of forces. The visco-elastic nature of living cells makes the developed model useful both for the simulations of inanimate fluidic droplets and living cells. Cells are modelled as drops, made by beads of fluid aggregates. With the proper implementation of attractive forces and “active particles”, drops can be active and spontaneously overcome their thermodynamic equilibrium status, closing the gap between inanimate and living matter behavior. In the dissertation, a deep investigation of the morphology and the forces involved in cell adhesion processes onto four different functionalized surfaces will be presented. Besides the work on cell adhesion, a study on neuritis growth, induced in the neuronal cell body by the presence of a chemical gradient on the surface, will be provided. The last part of my PhD thesis is concerned with the investigation of the guided movement and the morphological study of droplets onto solid surfaces, induced by the action of an external perturbation.