Elastomeric Tiles for the Fabrication of Inflatable Structures

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 5541 wileyonlinelibrary.com structures with homogeneous composition, but less effi cient at generating hollow, 3D structures, especially when they comprise multiple materials with different mechanical or physical properties. To fabricate 3D structures that incorporate elastomeric, infl atable components for use in the actuation of soft robots and machines, we are developing methods that are based on the assembly of prefabricated, standardized pieces: thin, 2D elastomeric tiles. Soft structures or devices fabricated using this approach can be “programmed,” by choosing tiles made of different materials, to undergo desired changes in shape on either pneumatic expansion or contraction. These structures can provide the appropriate types and ranges of motion useful in soft machines. In the demonstrations described in this paper, we fabricated elastomeric tiles of different compositions, using soft lithography, [ 8 ] and joined them to form hollow, 3D structures. When the interiors of these hollow structures were pressurized with gas, they expanded and changed shape; when evacuated they collapsed (via buckling) into quite different shapes. The patterns and choices of materials used in the tiles, the arrangement of the tiles in the assemblies, and the applied pressure are the critical parameters that dictate the shape and size of the infl ated (or evacuated) structures. Different structures can be generated by the infl ation of tile-based assemblies that are geometrically indistinguishable in their uninfl ated states. This methodology required the development of a technique which we call “soft” joinery to connect the tiles with leak-free bonds that were suffi ciently strong that they did not rupture at the pressures used (plus or minus ∼100 kPa). Soft joinery extends the strategies of joinery [ 9 ] used for the assembly of hard materials to the assembly of elastomeric tiles. Soft joinery works to connect elastomeric tiles using both dovetail joints that are common to hard materials, and a related but new structure— “double-taper dovetail joints”—that cannot be used with hard materials because these joints require elastomeric deformation of the tile during assembly. Using soft joinery and elastomeric tiles, we demonstrated a set of soft, shape-changing structures that may be useful for fabrication of soft machines and robots. Our approach enables the combination of elastomeric and hard polymers into structures with mechanical properties and functions defi ned by the designs of the structures, and the choices of the materials. Elastomeric Tiles for the Fabrication of Infl atable Structures