Extended Data Fig. 9: Roughness bias.
From: Spontaneous ordering of identical materials into a triboelectric series
a, We replot the data presented in Fig. 2a as a baseline. b, We measure the charge exchange between samples produced with a high roughness (about 1 μm) and unbiased samples (about 1 nm). High-roughness samples tend to charge positive against low-roughness samples and with a larger magnitude than unbiased against unbiased samples.
