Extended Data Fig. 2: Humidity bias.
From: Spontaneous ordering of identical materials into a triboelectric series
a, We reproduce the same data presented in Fig. 2a to use as a baseline. b, We measure the charge exchange between samples that have been stored at high humidity (roughly 90% RH) and unbiased samples (stored in the main chamber at 30% RH). Samples stored in high humidity charge slightly negatively against unbiased ones.
