Measuring shear-induced adhesion of gecko-inspired fibrillar arrays using scanning probe techniques

The natural ability of geckos and spiders to climb almost all surfaces using the compliant, nano-structured components on their feet provides motivation for making bio-inspired adhesives. The goal of the studies in this paper is to create an analytical technique for improving the ability to characterize dry adhesives modeled after these biological systems. The technique described herein uses a scanning probe microscope to manipulate a flat test surface in contact with biomimetic fibrillar arrays while monitoring the adhesion forces. Adhesion forces were measured after both normal contact and shear-induced contact between the nano-structured fibrils and the test surface. Results confirm that the adhesion forces are higher for bio-inspired adhesives after a shear-induced contact. Variations in these forces can be measured across the sample with micrometer-scale lateral resolution. This method of analysis can be extended to evaluate bio-inspired dry adhesives with realistic mechanisms of attachment utilized in robotic and similar applications of these materials.