Publications in Scientific Journals:
S. Mertens, A. Hemmi, S. Muff, O. Gröning, S. De Feyter, J. Osterwalder, T. Greber:
"Switching stiction and adhesion of a liquid on a solid";
When a gecko moves on a ceiling it makes use of adhesion and
stiction. Stiction-static friction-is experienced on microscopic
and macroscopic scales and is related to adhesion and sliding
friction1. Although important for most locomotive processes, the
concepts of adhesion, stiction and sliding friction are often only
empirically correlated. A more detailed understanding of these
concepts will, for example, help to improve the design of increasingly
smaller devices such as micro- and nanoelectromechanical switches2.
Here we show how stiction and adhesion are related for a liquid drop
on a hexagonal boron nitride monolayer on rhodium3, by measuring
dynamic contact angles in two distinct states of the solid-liquid
interface: a corrugated state in the absence of hydrogen intercalation
and an intercalation-induced flat state. Stiction and adhesion can be
reversibly switched by applying different electrochemical potentials
to the sample, causing atomic hydrogen to be intercalated or not.
We ascribe the change in adhesion to a change in lateral electric
field of in-plane two-nanometre dipole rings4, because it cannot
be explained by the change in surface roughness known from the
Wenzel model5. Although the change in adhesion can be calculated
for the system we study6, it is not yet possible to determine the
stiction at such a solid-liquid interface using ab initio methods.
The inorganic hybrid of hexagonal boron nitride and rhodium is
very stable and represents a new class of switchable surfaces with
the potential for application in the study of adhesion, friction and
Created from the Publication Database of the Vienna University of Technology.