title: The undulation force; theoretical results versus experimental demonstrations.
abstract: In 1978 Wolfgang Helfrich published a paper (Helfrich W. Z Naturforsch 1978; 33a:305) where he introduced the notion of an undulation force between bilayers. This is caused by thermal excitations of the bending modes being restricted by the presence of neighboring layers. Although there is now a consensus on the qualitative picture put forward by Helfrich there is still a debate concerning the quantitative aspects. We discuss in particular the distance dependence of the interaction and also the value of the numerical coefficient of the force law derived by Helfrich.
authors.affiliation: Division of Physical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden. Electronic address: hakan.wennerstrom@fkem1.lu.se.
authors.forename: Håkan
authors.initials: H
authors.lastname: Wennerström
authors.affiliation: Division of Physical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden. Electronic address: ulf.olsson@fkem1.lu.se.
authors.forename: Ulf
authors.initials: U
authors.lastname: Olsson
keywords: Fluid membranes