A micro-nano-rheometer for the mechanics of soft matter at interfaces.

We present a nano-rheometer based on the dynamic drainage flow between a sphere and a plane from bulk regime to highly confined regime. The instrument gives absolute measurements of the viscosity of simple liquids in both regimes. For complex fluids, the measurements involve the viscosity and the elastic modulus. The device operates on distances ranging over four orders of magnitude from 1 nm to 10 μm, bridging rheological properties from the macroscopic to the molecular scale. This allows to measure an hydrodynamic or visco-elastic boundary condition and to explore the causes of the boundary condition at the microscopic level.