Dry adhesives are remarkably robust and when incorporated as part of a complete system, can not only displace materials in existing materials, but will open up new frontiers in engineering design that are currently limited by the lack of available materials.
When dry adhesives were first developed, the performance was rather limited. For example, a common route to produce a dry adhesive is to begin with a layer of sacrificial polymer such as PMMA on a silicon substrate, etch the surface into a pillar array using electron beam lithography, and pour a soft elastomer such as PDMS into the mold. After lifting off, the surface of the PDMS will contain a repeating array of micro-pillars, typically with diameter and height on the order of 500 nm, and distance between pillars of about a micron. These micro-pillar arrays are designed to mimic the setae structure of geckos and typically have shear strengths on the order of 3 pounds per square inch (psi).
AAI adopted a different strategy - rather than mimicking the appearance of the gecko foot, we sought to mimic the mechanics of the adhesive process using different materials. By tuning the mechanical properties of the nanofibers and compliance of the nanofiber mat, AAI’s dry adhesives have shown shear strength in excess of 120 psi while retaining easy removal by peeling and reusability in many cases.
The simplest demonstration of an adhesive is to see how much it can pick up. Unlike many of the other small scale technologies, AAI’s approach to producing dry adhesives can be used to produce large areas of material with real performance. Check out our videos to see demonstrations of dry adhesives used to lift computer monitors in various configurations, and still retaining clean, easy peel on soft surfaces, including cardboard!
Electrospinning dry adhesives is a platform technology that offers a number of opportunities to develop novel adhesives with unique properties. These dry adhesives have been found to exhibit remarkable self-adhesion, and the performance is retained even when joined underwater!