Printed Active Liquids*

We present printed, all-liquid, water/oil and water/water systems. Our constructs are structured by the assembly of nanoparticles and polymers at the liquid-liquid interface. The insoluble layers that these assemblies form have significant, highly tunable shear moduli (order 0.1-10 N/m) that can be used to structure liquid-liquid systems into a wealth of shapes. We cover the materials used to generate these threads, namely polyelectrolytes, nanoparticles and, nanoparticle surfactants. Finally, we discuss the encapsulation of active and living systems in the printed constructs, most notably colonies of Geobacter Sulferreducens and dispersions of active tubulin filaments that are rendered motile by ATP-consuming molecular motors. Of particular interest is the effect of the soft confining walls of the tubules on both the coherence of the motion of the tubulin filaments, as well as the deformation modes of the printed structures due to the motion of the active rods.