Based on the theoretical analysis on a growing bubble

a technique for measuring surface dilational viscosity is proposed. The growing process of the bubble is captured by videoimage technique. An edge-tracing algorithm using a local threshold and a method for profile optimization are used applied to determine the shape of the growing bubble. A device for measuring the dynamic surface tension from the profile of a growing bubble is set up

so that the dynamic surface tension can be determined directly as a function of time. The surface dilational viscosity of the solutions is determined through the rate of change of dynamic surface tension with respect to the rate of surface expansion. The surface dilational viscosity of sodium dodecyl sulfate (SDS) solution is measured. The data and those with different rates of surface deformation from the literature indicate that the surface exhibits surface reological property.