Patent ID: 7926326

Claim:
A measurement system for measuring rheological properties of a fluid interface, comprising: a cylindrical chamber having a chamber wall whose inner surface defines an outer chamber radius with respect to an axis of the cylindrical chamber, the cylindrical chamber configured to retain a sub-phase that supports the fluid interface; an inner cylinder disposed within the cylindrical chamber and concentric with an axis of the cylindrical chamber, the inner cylinder having an outer surface defining an inner cylinder radius, wherein the inner cylinder is mechanically coupled to the chamber wall to prevent relative rotational or translational movement between the inner cylinder and chamber wall; a circular ribbon concentric with and suspended between the inner cylinder and chamber wall and configured to contact the interface, wherein the circular ribbon has a ribbon radius (R c ) that is intermediate between the inner cylinder (R i ) and outer (R o ) chamber radii, wherein the system is configured to impart a relative rotation to the circular ribbon with respect to the chamber wall and inner cylinder, wherein the circular ribbon defines an inner region that lies between the circular ribbon and inner cylinder and an outer region that lies between the circular ribbon and chamber wall, and wherein a ratio of the ribbon radius, inner chamber radius, and outer chamber radius is designed to yield an average shear rate in the inner region that is the same as an average shear rate in the outer region.