Microfabricated deflection tensiometers for insoluble surfactants

摘要

We describe a technique that enables sensitive surface pressure measurements of insolublensurfactants with small quantities in enclosed systems. We microfabricate free-floatingnmicrotensiometers that rest at liquid interfaces. Our devices isolate clean interfaces fromnsurfactant-laden ones and deform in response to the surface pressure difference. Elastic beam theorynenables straightforward interpretation of the measurements and the deliberate engineering of thensensitivity and dynamic range of the device. Surface pressure isotherms for model surfactantnmonolayers measured using our microtensiometer show excellent agreement with a conventionalnWilhelmy plate.