title: Instabilities in droplets spreading on gels.
abstract: We report a novel surface-tension driven instability observed for droplets spreading on a compliant substrate. When a droplet is released on the surface of an agar gel, it forms arms or cracks when the ratio of surface-tension gradient to gel strength is sufficiently large. We explore a range of gel strengths and droplet surface tensions and find that the onset of the instability and the number of arms depend on the ratio of surface tension to gel strength. However, the arm length grows with an apparently universal law L proportional t(3/4).
authors.affiliation: Department of Physics and Center for Nonlinear and Complex Systems, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Daniels
authors.forename: Shomeek
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Houseworth
authors.forename: Robert P
authors.initials: RP
authors.lastname: Behringer