  Friction-induced energy dissipation impedes the performance of nanoscale
devices during their relative motion. Nevertheless, an ingeniously designed
structure which utilizes graphene topping can tune the friction force signal by
inducing local strain. The present work reports capping of graphene over Si
grooved surfaces of different pitch lengths from sub-nanoscale (P=40 nm) to a
quarter of a micron (P= 250 nm). The variation in the pitch lengths induces
different strains in graphene revealed by scanning probe techniques, Raman
spectroscopy and molecular dynamics (MD) simulation. The asymmetric straining
of C-C bonds over the groove architecture is exploited through friction force
microscopy in different directions of orthogonal and parallel to groove axis.
The presence of graphene lubricates the textured surface by a factor of 10 and
periodically dissipated friction force, which was found to be stochastic over
the bare surface. For the first time, we presented transformation of the
lubrication into an ultra-low friction force by a factor of 20 over the crest
scanning parallel to the groove axis. Such anisotropy is found to be
insignificant at the bare textured system, clearly demonstrating the
strain-dependent regulation of friction force. Our results are applicable for
graphene, and other 2D materials covered corrugated structures with movable
components such as NEMS, nanoscale gears and robotics.
