Influence of humidity on tribo-electric charging and segregation in shaken granular media.

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We study the effect of humidity on the charge accumulation of polymer granulates shaken vertically in a stainless steel container. This setup allows us to control the humidity level from 5% to 100%RH while performing automated charge measurements in a Faraday cup directly connected to the shaking container. We find that samples of approximately 2000 polymer spheres become highly charged at low humidity levels (<30%RH), but acquire almost no charge for humidity levels above 80%RH. The transition between these two regimes does depend on the material, as does the sign of the charge. For the latter we find a correlation with the contact angle of the polymer with only very hydrophilic particles attaining positive charges. We show that this humidity dependence of tribo-charging can be used to control segregation in shaken binary mixtures.





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Schella, André, Stephan Herminghaus and Matthias Schröter (2017). Influence of humidity on tribo-electric charging and segregation in shaken granular media. Soft matter, 13(2). pp. 394–401. 10.1039/c6sm02041k Retrieved from

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Matthias Schroter

Visiting Associate Professor of DKU Studies at Duke University

I am interested in (in order of appearance): Greek philosophy, pattern formation, minimal music, granular matter, meditation, X-ray tomography, machine learning,  ....

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