2D Patterns of Active Stress ascribe 3D Deformations of Driven Actomyosin Networks

During morphogenesis 2D active stresses in actomyosin networks can lead to 3D deformation of epithelial sheets. Though there is consensus on role of stress, how in-plane activity morphs epithelial sheets out of plane is not clearly understood. To understand this relation, we design an invitro actomyosin network with tunable mechanical stiffness and activity. The active stresses can be locally programmed into the 2D actomyosin sheets by photoactivation of myosin motors. We demonstrate that an interplay between mechanics of sheet and activity leads to controlled 3D deformations. We show that the extent of 3D deformation of network is proportional to activity, but varies non-monotonically with stiffness. By controlling the shape and duration of activation protocol, we can create 3D deformations of various shapes with positive, negative, or zero gaussian curvature. Through experiments and agent-based simulations we show that local inhomogeneities in stiffness of actomyosin sheet are responsible for activity-driven out of plane deformations. These results open an arena for designing bio-inspired smart active materials with programmable deformations.