Disclosing the Microscopic Picture: An Interdisciplinary Investigation of Friction and Wetting Using a Gecko-Inspired Tape

We propose an innovative approach to teaching friction. Our approach aims to educate students on its microscopic nature by highlighting its origin in intermolecular interactions. We have designed a teaching sequence (TS) based on a set of experimental investigations of the properties of a gecko-inspired tape at different length scales. The TS has been conceived to unravel the peculiar behavior of this man-made, commercially available biomimetic material and to train students to identify the connection between the micrometer-scale patterning and the peculiar tribological properties. Specifically, our approach compares friction (and adhesion) to wetting, occurring at solid/solid and solid/liquid interfaces, respectively. The aim is to scaffold a correct mental model of real interfaces and disclose the common origin of both phenomena in intermolecular interactions. The TS has been devised according to the design-based research scheme and it was inspired by the Investigative Science Learning Environment (ISLE) and the 5E paradigms. It has been tested and tuned with students at level 3 in the International Standard Classification of Education (ISCED), during several on-campus stages. We report here the details and results of pre- and post-tests, which demonstrate the effectiveness of our method. Specifically, we measure success in terms of the students' comprehension of the link between contact area and friction and of the role of intermolecular forces. We are confident that the learning experience with our TS will lead students to recognize the enormous potential impact of surface patterning in technological applications, in a curiosity-driven manner that will likely result in students' interest in quantitative studies of science and technology.