Toward Zero Static Friction at the Microscale.

Static friction, a ubiquitous physical phenomenon, plays a significant role in natural processes and industrial applications. Its influence is particularly notable in the field of controlled micromanipulation and precision manufacturing, where static friction often exceeds kinetic friction and leads to material damage and unpredictable behaviors. In this study, we report the first experimental observation of the elimination of static friction peak in sliding micrometer contacts of layered materials, achieved through a technique involving selective etching of the amorphous edges of single crystalline surfaces. Our findings are consistent with theoretical models and simulations that predicted the absence of static friction between two atomically flat, pristine, weakly interacting, incommensurate solid surfaces. In this state, thermally induced spontaneous actuation in graphite homogeneous junctions was observed at temperatures slightly above room temperature (around 40 °C), with contact sizes up to 100  μm^{2}. These results have significant implications for improving our understanding and control of static friction, opening up promising opportunities for the application of micromechanical devices and precision mechanical systems.