Robust large-area synthetic dry adhesives

Although bioinspired dry adhesives are nearly a decade old, there are to date no available commercial products based on these materials. Although commercialization is a while off, great strides have been made with respect to physical modeling of actual gecko adhesion, synthetic fabrication methods, and introduction of capabilities like self-cleaning, directional behavior, and superhydrophobic behavior into synthetic variations. Despite the large number of fabrication methods available, there are still specific difficulties in manufacturing these materials that limit their use in commercial applications. In this paper, we describe how a simple manufacturing technology can be adapted to create relatively high-strength adhesives at low costs on large areas. Our focus is on determining how larger diameter, easily manufactured fiber shapes can be best designed to adhere to smooth surfaces. This manufacturing method has been used to successfully produce adhesives from a variety of materials, and we demonstrate how it can be adapted to form the microscale mushroom-shaped fibers necessary for strong adhesion without needing vacuum casting. Additionally, we present practical lessons learned in what makes an effective dry adhesive for industrial applications, where the expected surfaces to be encountered are mostly flat and rigid in comparison to the adhesive material. Finally, the importance of tip roughness due to manufacturing methods is demonstrated to be a significant source of adhesion reduction which must be accounted for when designing these materials.