Langmuir trough with four movable barriers

A new type Langmuir trough has been constructed, in which a monolayer on water is enclosed by four polytetrafluoroethylene (PTFE) tapes, independently movable, floating on the water. This arrangement allows a uniform film compression and a study of the stress inhomogeneity under purely compressional or shear strain. The system does not require a delicate water level adjustment. It is capable of sustaining a high surface pressure and easy to operate.