Assembly and mechanical analysis of 3D photodetector structures from 2D materials. a Schematic illustration of processes for fabricating the 3D systems. b FEA results describing the formation of arrays of photodetectors based on graphene and MoS2 in the form of an octagonal prism, and corresponding colorized SEM images of the final configuration including MoS2 (green), graphene (light gray), and SU-8 (gray). c, d Similar FEA results for the cases of an octagonal prismoid and a hemisphere. Colors represent the magnitude of the maximum principal strain. e Central angle and radius of a cross-section of the hemisphere in d vs. the released pre-strain. Here, the insets denote an intermediate state (εreleased = 21.4%) and the final state (εreleased = 46%) of pre-strain release, with the dashed and solid lines representing the profiles from FEA and fitting arcs, respectively. f FEA results and analytic predictions of the height of three photodetector structures in b–d. g Computational study of tensile strain applied to the SU-8, graphene, and MoS2 layers vs. pre-strain during the 3D assembly (squares, circles, and triangles denote the octagonal frustum, hemisphere, and octagonal prism, respectively). h Experimentally measured variation in the resistance in graphene during repeated buckling processes