Dewetting of cellular monolayers.

We investigate the physical principles of cellular layer stability. We show that cohesive cellular layers deposited on non-adhesive substrates are metastable and "dewet" by nucleation and growth of dry patches. The dewetting process can be induced either chemically by a non-adhesive surface treatment or, unlike simple liquids, physically by a decrease in the substrate rigidity. We thus unveil two mechanisms by which the integrity of cellular layers can be compromised. We interpret the opening dynamics by an analogy with the dewetting of viscous films. This analogy can be exploited to estimate parameters characterizing the mechanical response of a cellular layer.