Abstract: An aerodynamic or hydrodynamic wall surface has an array of fibrillar structures disposed on and extending from the wall surface, wherein each fibrillar structure comprises a stalk and a tip. The stalk has a first end and a second end, wherein the first end is attached to the wall surface, and the stalk is oriented with respect to the wall surface at a stalk angle between approximately 1 degrees and 179 degrees. The tip has a first side and a second side, wherein the first side is attached proximate to the second end of the stalk, the tip has a larger cross-sectional area than the stalk, and the second side comprises a substantially planar surface that is oriented with respect to the stalk at a tip angle between approximately 0 degrees and 90 degrees.

Abstract: This invention identifies important geometric parameters of an adhesive microfiber with mushroom-shaped tip for improving and optimizing adhesive ability. The magnitude of pull-off stress is dependent on a wedge angle ? and the ratio of the tip radius to the stalk radius ? of the mushroom-shaped fiber. Pull-off stress is also found to depend on a dimensionless parameter x, the ratio of the fiber radius to a length-scale related to the dominance of adhesive stress. Finally, the shape of edge tip, where the surface and sides of the mushroom-shaped tip join, is a factor that impacts strength of adhesion. Optimizing ranges for these parameters are identified.

Abstract: This invention identifies important geometric parameters of an adhesive microfiber with mushroom-shaped tip for improving and optimizing adhesive ability. The magnitude of pull-off stress is dependent on a wedge angle ? and the ratio of the tip radius to the stalk radius ? of the mushroom-shaped fiber. Pull-off stress is also found to depend on a dimensionless parameter x, the ratio of the fiber radius to a length-scale related to the dominance of adhesive stress. Finally, the shape of edge tip, where the surface and sides of the mushroom-shaped tip join, is a factor that impacts strength of adhesion. Optimizing ranges for these parameters are identified.

Abstract: The present invention is a method that (i) allows for creating micro and/or nanostructures on either planar or non-planar three-dimensional surfaces in a single molding step, and (ii) allows for the molded production of complex high-aspect ratio micro and/or nanostructures including but not limited to cylinders, conical structures, low aspect-ratio channels, bumps, or posts. An example of such a complex structure are high aspect ratio pillars with enlarged “mushroom-shaped” or undercut tips which demonstrate enhanced, repeatable adhesion and shear strength on a variety of substrates when compared with other micro and/or nanostructures and unstructured materials. The mold of such a material requires an “undercut” feature that cannot be produced using typical micro/nano-molding processing techniques.

Abstract: This invention identifies important geometric parameters of an adhesive microfiber with mushroom-shaped tip for improving and optimizing adhesive ability. The magnitude of pull-off stress is dependent on a wedge angle ? and the ratio of the tip radius to the stalk radius ? of the mushroom-shaped fiber. Pull-off stress is also found to depend on a dimensionless parameter x, the ratio of the fiber radius to a length-scale related to the dominance of adhesive stress. Finally, the shape of edge tip, where the surface and sides of the mushroom-shaped tip join, is a factor that impacts strength of adhesion. Optimizing ranges for these parameters are identified.

Abstract: The present invention is a method that (i) allows for creating micro and/or nanostructures on either planar or non-planar three-dimensional surfaces in a single molding step, and (ii) allows for the molded production of complex high-aspect ratio micro and/or nanostructures including but not limited to cylinders, conical structures, low aspect-ratio channels, bumps, or posts. An example of such a complex structure are high aspect ratio pillars with enlarged “mushroom-shaped” or undercut tips which demonstrate enhanced, repeatable adhesion and shear strength on a variety of substrates when compared with other micro and/or nanostructures and unstructured materials. The mold of such a material requires an “undercut” feature that cannot be produced using typical micro/nano-molding processing techniques.