Provided are systems and methods for the post-treatment of dry adhesive microstructures. The microstructures may be post-treated to comprise mushroom-like flaps at their tips to interface with the contact surface. In some aspects, a change in material composition of the microstructures in a dry adhesive may affect mechanical properties to enhance or diminish overall adhesive performance. For example, conductive additives can be added to the material to improve adhesive performance. In other aspects, microstructures comprising conductive material may allow for preload engagement sensing systems to be integrated into the microstructures.

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.

A dry adhesive and a method of forming a dry adhesive. The method includes forming an opening through an etch layer and to a barrier layer, expanding the opening in the etch layer at the barrier layer, filling the opening with a material, removing the barrier layer from the material in the opening, and removing the etch layer from the material in the opening.

An activatable wrap material includes a film material a first side and a second side opposite the first side. The wrap material includes a plurality of protrusions extending outward from the first side of the wrap material and oriented in a pattern across the first side of the wrap material and a plurality of planar portions defined within the first side of the wrap material and throughout the plurality of protrusions. The wrap material exhibits an average peel adhesion force, when activated against a surface, between about 1.50 g/in to about 3.25 g/in. The wrap material further exhibits an average roll unwind force, when wound on a roll, between about 1.50 g/in to about 5.0 g/in. The wrap material also exhibits an average blocking force, when contacting itself, between about 0.4 g/in.sup.2 to about 1.30 g/in.sup.2.

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.

Provided is an adhesive member including: a base material having an uneven shape on at least one surface; and a surface layer covering at least a portion of the surface having the uneven shape on the base material.

The present invention provides a shear gripper device using fibrillar, gecko-inspired adhesives that have the characteristics of being non-tacky in its default state and requiring no normal force to grip a surface. The adhesion is turned on by the applied shear load, and off as the shear load is removed. The shear adhesive gripper is able to grasp large, deformable or delicate objects using a delicate touch.

Provided are systems and methods for the post-treatment of dry adhesive microstructures. The microstructures may be post-treated to comprise mushroom-like flaps at their tips to interface with the contact surface. In some aspects, a change in material composition of the microstructures in a dry adhesive may affect mechanical properties to enhance or diminish overall adhesive performance. For example, conductive additives can be added to the material to improve adhesive performance. In other aspects, microstructures comprising conductive material may allow for pre-load engagement sensing systems to be integrated into the microstructures.

Resilient members having near-surface architectures including microstructures for controlling friction are provided. A film-terminated array of fibrils having a sharp film/fibril juncture exhibits an unexpectedly large enhancement of adhesion, static friction and sliding friction. The enhancement is provided against so rough indenters. A film-terminated array of elongated ridges and valleys unexpectedly exhibits low adhesion, and an unexpectedly large enhancement of sliding friction. The film-terminated ridge/valley design provides an anisotropic structure with direction-dependent frictional properties. The increase in sliding friction force varies as a function of interfibrillar spacing, and corresponds to a mode is in which buckling of the terminal film occurs. The near surface architectures may be designed with varying scales and varying parameters to provide performance characteristics tailored to various applications. By way of example, the film-terminated ridge/valley array may be incorporated in motor vehicles tires to provide low rolling resistance and high sliding friction allow for high-performance braking during vehicle operation.

A microstructured pressure-sensitive surface is described comprising a Wenzel-Cassie hydrophilic-hydrophobic zone structure and capillary action with improved peel strength. The capillary action is enhanced by the Wenzel-Cassie zone creation, and the barrier energy to disruption of the Wenzel-Cassie zone is increased by the capillary action. The micro-structured surfaces of the present invention create water zones of exclusion, where entropic effects reinforce Wenzel-Cassie zone stability, creating a suction effect that conforms the microstructure surface to a target surface.