Soft Matter Seminar: Dr. Itay Griniasty

Dr. Itay Griniasty from the Physics Department at Cornell University

“Dynamics of shape shifting surfaces – inverse design and theory.”

Abstract: An important emerging strategy for manufacturing microscopic and soft machines is fabricating them using two dimensional lithographic and printing techniques. The vision is that post printing, these sheets will transform or hop between various conformation via local folding and stretching to achieve complex actions. In this talk I will describe two strategies I developed to realize this vision.

1) An anisotropic deformation applied inhomogeneously throughout a sheet allows the design of a single sheet that can deform into multiple surface geometries upon different actuations. The key to this approach is the development of an analytical method for solving this multivalued inverse problem. As a proof of concept of this strategy, I will demonstrate a design of a simple swimmer capable of moving through a fluid at low Reynolds numbers.

2) Decorating a shape shifting system with magnets allows it to snap between multiple states. The magneto elastic machine’s motion is primarily guided by a designed magnetic energy landscape. I will show that by operating near bifurcations of the resulting dynamics we can transition between multiple distinct mechanically equilibrated states. An advantage of working near bifurcations is that small variations in the control parameters can result in large changes to the system’s state. The challenge, however, is designing magnetic landscapes with bifurcations between multiple states, because such bifurcations are exponentially rare in the design space as the number of associated equilibrium states increases. Towards this end I have developed an efficient algorithm that finds magnetic landscapes with bifurcations between an arbitrarily number of states. I will demonstrate an implementation of this strategy in a magneto elastic machine operating near a butterfly bifurcation between three states.

Time permitting I will also describe a third strategy where a novel pluripotent kirigami pattern allowing a sheet to transform along arbitrary paths between surface geometries.”