Bending test experiment on suspended ultrathin MoS
sheets. (a) Force versus deformation traces measured by pushing and pulling at the center of the suspended part of MoS2 nanosheets with 5, 10, and 20 layers in thickness. The slope of the traces around zero deformation is marked by a dotted line. (b) Effective spring constant as a function of the thickness measured for 31 MoS2 suspended nanosheets with thickness ranging from 25 down to 5 layers. Data points sharing color and symbol correspond to suspended nanosheets from the same MoS2 flake. The solid black line shows the calculated relationship with Equation 2 using E = 0.30 TPa and T = 0.15 N/m. The gray area around the solid black line indicates the uncertainty of E and T: ΔE = ± 0.10 TPa and ΔT = ± 0.15 N/m.