  The control of strain in two-dimensional materials opens exciting
perspectives for the engineering of their electronic properties. While this
expectation has been validated by artificial-lattice studies, it remains
elusive in the case of atomic lattices. Remarkable results were obtained on
nanobubbles and nano-wrinkles, or using scanning probes; microscale strain
devices were implemented exploiting deformable substrates or external loads.
These devices lack, however, the flexibility required to fully control and
investigate arbitrary strain profiles. Here, we demonstrate a novel approach
making it possible to induce strain in graphene using polymeric micrometric
artificial muscles (MAMs) that contract in a controllable and reversible way
under an electronic stimulus. Our method exploits the mechanical response of
poly-methyl-methacrylate (PMMA) to electron-beam irradiation. Inhomogeneous
anisotropic strain and out-of-plane deformation are demonstrated and studied by
Raman, scanning-electron and atomic-force microscopy. These can all be easily
combined with the present device architecture. The flexibility of the present
method opens new opportunities for the investigation of strain and
nanomechanics in two-dimensional materials.
