MEAM Seminar: “Examples of Elasto-Capillary Mediated Interactions on Thin Elastic Film”

I plan to tell two short stories. The first story is about a new drop fluidics that uses a deformable and stretchable elastomeric film as the platform. Such a soft film decorated with magnetic particles can be deformed locally with an external magnetic field. When these deformations are coupled with capillary force, small liquid drops can be moved over the platform over long distances efficiently and accurately. The resulting drop fluidics could be suitable for the digital control of drop motion by simply switching on and off the local magnetic fields applied at different positions underneath the elastomeric film in a Boolean sequence.

The second story is about the interaction of two beads on the surface of a thin elastic film supported on a pool of liquid. Here, the excess energy of the surface due to the curvature of the stretched film induces attraction of the beads. It is found that the hysteresis of adhesion between the beads and the elastic film retard the motion of the objects, which, however, can be reduced by introducing a thin hydrogel layer atop the elastic film. Morphological instabilities in the gel create corrugated paths to the motion, thus causing the particles to aggregate along the patterns thus developed. These observations suggest that a deformable elastic film affords an effective model system to study elasticity and mediated interaction of particles on its surface.