Extended Data Figure 3: Thermal motion of graphene cantilever gold pads.

a, Time trace of the x position of the gold pad centroid on a 40 µm × 10 µm graphene cantilever, showing the first 20 s of a 20-min trace. The x direction is perpendicular to the profile of the gold pad, as indicated in the inset. b, PSD (S_xx ) of the full 20-min time trace from a. The blue data points were included in the fit to the Brownian motion PSD function (dashed line); the red data points from about 10⁻³ Hz to about 10⁻¹ Hz were excluded, because they show considerable 1/f noise as a result of the motion of the probe holding the cantilever. We integrate the fitted function S_xx to determine . For the device shown, = (130 nm)², the spring constant k = 2.4 × 10⁻⁷ N m⁻¹, and the bending stiffness κ = 3 keV.