Fluid mediated assembly of pixelated materials

Capillary imbibition plays a critical role in a number of natural and engineering systems, from drinking strategies and plant vasculature to transport in porous media and emulsion generation. Here we fabricate novel soft materials by harnessing this phenomenon to draw curing elastomers through confined geometries. We first rationalize the fluid mechanics at play: as a pressure gradient drives flow from an inlet into a Hele-Shaw cell, we predict the dynamics and final state of the system as a function of interfacial tension, viscous effects, and curing properties of the chosen material. When inlets are close enough for their respective flows to interact, we observe the formation of connected networks, including angular structures such as polyhedra. We then explore the inverse case in which we determine the inlet configuration necessary to achieve a desired pattern. Extending this methodology to different types of materials opens the door for the fabrication of architected soft sheets, whose structure can provide superior properties and functionality.