A common theoretical basis for surface forces apparatus, osmotic stress, and beam bending measurements of surface forces

In the last two decades, several techniques for measuring the interactions of surfaces or macromolecules through a solvent phase have been developed. These methods include the surface forces apparatus, the osmotic stress device, and most recently a beam bending experiment. This paper summarizes a statistical mechanical framework that can be used to compare and contrast the different methods. We demonstrate that while the SFA provides an elegant direct measure of surface forces in a single ideal pore, the OS and BB methods provide unique in situ measurements of the solvation force. These in situ measurements provide information about self-assembly in solution (OS) and can be used to characterize pore morphology in microporous thin films (BB).