Programmable shape morphing of drying foods via symmetry breaking.

We investigate how differential drying can be programmed to induce shape morphing in edible materials. As a prototypical geometry we consider a planar disk composed of two materials with strongly contrasting elastic moduli, readily fabricated by a dual-nozzle 3D printer. Because the two materials shrink at different rates during drying, residual stresses build up and trigger buckling. Our finite-element model, which couples large deformations to heat- and mass-transfer processes, predicts that a simple disk with a compliant core and stiff rim spontaneously transforms into a hyperbolic paraboloid. Our design strategy shows how with symmetry-breaking strategies one can tune the final shape. The design principles extend naturally to other cooking methods such as baking, boiling, frying, and microwave heating.