Soft robots, made from elastomers, easily bend and flex, but deformability constraints severely limit navigation through and within narrow, confined spaces. Using aqueous two-phase systems we print water-in-water constructs that, by aqueous phase-separation-induced self-assembly, produce ultrasoft liquid robots, termed aquabots, comprised of hierarchical structures that span in length scale from the nanoscopic to microsciopic, that are beyond the resolution limits of printing and overcome the deformability barrier. The exterior of the compartmentalized membranes is easily functionalized, for example, by binding enzymes, catalytic nanoparticles, and magnetic nanoparticles that impart sensitive magnetic responsiveness. These ultrasoft aquabots can adapt their shape for gripping and transporting objects and can be used for targeted photocatalysis, delivery, and release in confined and tortuous spaces. These biocompatible, multicompartmental, and multifunctional aquabots can be readily applied to medical micromanipulation, targeted cargo delivery, tissue engineering, and biomimetics.
Keywords: All-water robotics; aqueous phase separation; hierarchical self-assembly; multicompartmental reactors; water-in-water 3D printing.