Résumé:

Red blood cells under shear flow present a specific swinging motion superimposed to a fluid-like tanktreading motion. Swinging is hypothesized to originate from periodic storage of shear energy in the cell membrane. Here we designed giant unilamellar vesicles with two lipid phases separated by a contact line, which swing and tanktread like red cells. We propose a model that quantitatively fits our data, finds the value of the contact-line tension and shows that swinging is due to the storage of elastic energy associated with the periodic modulation of the contact-line length during tanktreading.