Fig. 1.

Flexible anisotropic strain sensor made of rationally assembled bilayers of periodically wrinkled and cracked CNT–GO hybrid film and aligned CNT arrays. a Schematic illustration of the fabrication process. b Schematic illustration of the bilayers of wrinkled and crack-bridging structures. c SEM images of bilayers showing the CNTs aligned in T-direction with underlying wrinkles in L-direction: wrinkle ridge in inset. d SEM image of CNT–GO film showing both extensive wrinkles and microcracks. e SEM image of aligned CNT arrays. f Optical and SEM images of bilayer film showing the bottom microcracks bridged by the top-aligned CNTs