Late stages of the pearling instability in lipid bilayers

We have studied the late stages of the 'pearling instability' in lipid bilayers, which is brought on by applying laser tweezers to a cylindrical vesicle. This produces a front that propagates down the vesicle, leaving behind it bilayer-covered droplets separated by thin tubes, which appear under the microscope as pearls on a string. At later times, the 'pearls' are observed to drift slowly towards the 'trap' (the spot where the tweezers are applied, into which the surfactant is drawn). We model the hydrodynamics of the drifting pearls as a combination of translation of the string of pearls, and 'slipping' of the bilayer skin over the pearls, to relate the speed of the pearls to the underlying flux of the surfactant into the trap.