> Among all the parameters they investigated, only one provided any hint at all: they spotted discrete changes in the materials' surface roughness at the nanoscopic scale.
> More concretely, they showed that contacts smoothed the tiniest bumps on a material's surface. How this causes contact electrification the team does not know, but as it is the only change they could detect, it is highly suggestive.
That suggests future experiments require some way to supply samples with where their surfaces (not just their charge) are in a known starting state. I'd say "just grind it down", but whatever you're grinding with also needs to have a standard state.
Perhaps something where a grinding/smoothing material is melted and then re-solidified between uses?
After 200 contacts they detected persisting tribological electrical series ranking, but then found surface roughness changes too. So.. it's correlation heading to a theory of causation.
> Among all the parameters they investigated, only one provided any hint at all: they spotted discrete changes in the materials' surface roughness at the nanoscopic scale.
> More concretely, they showed that contacts smoothed the tiniest bumps on a material's surface. How this causes contact electrification the team does not know, but as it is the only change they could detect, it is highly suggestive.
That suggests future experiments require some way to supply samples with where their surfaces (not just their charge) are in a known starting state. I'd say "just grind it down", but whatever you're grinding with also needs to have a standard state.
Perhaps something where a grinding/smoothing material is melted and then re-solidified between uses?
After 200 contacts they detected persisting tribological electrical series ranking, but then found surface roughness changes too. So.. it's correlation heading to a theory of causation.