Designing self-propelled, chemically active sheets: Wrappers, flappers, and creepers.

Catalyst-coated, hard particles can spontaneously generate fluid flows, which, in turn, propel the particles through the fluid. If the catalyst-coated object were a deformable sheet, then the self-generated flows could affect not only the sheet's motion but also its shape. By developing models that capture the interrelated chemical, hydrodynamic, and mechanical interactions, we uncover novel behavior emerging from the previously unstudied coupling between active, soft sheets and the surrounding fluid. The chemically generated flows "sculpt" the sheet into various forms that yield different functionalities, which can be tailored by modifying the sheet's geometry, patterning the sheet's surface with different catalysts, and using cascades of chemical reactions. These studies reveal how to achieve both spatial and temporal controls over the position and shape of active sheets and thus use the layers to autonomously and controllably trap soft objects, perform logic operations, and execute multistage processes in fluid-filled microchambers.