Mechanics of Active Foam: Local Energy Injection in an Addressable 2D Foam

Mechanics of Active Foam: Local Energy Injection in an Addressable 2D Foam Laurel Kroo, Department of Mechanical Engineering, Stanford University Manu Prakash, Department of Bioengineering, Stanford University DOI: The study of foam has inspired many insights into cellularized materials, including biological tissue. While cellular sheets superficially resemble passive foam structures, cells incorporate many layers of internal feedback. Here we show the development of an abiotic but “active” foam, governed by comparatively simple rules and programmatically controllable. The platform allows air to be periodically injected and removed from individual voxels in a 2D soap foam in a Hele-Shaw cell. This video shows that cyclic energy injection leads to fascinating global dynamics, influenced by the presence of neighbor-swapping topological events (T1). Just like our understanding of active fluids and active solids has brought new light to a multitude of problems - active foam provides a new platform to ask questions both in foam physics and, by analogy, in tissue mechanics. See other videos from the 2018 Gallery of Fluid Motion: