US Patent 7059176 Resonant tube viscosity sensing device

A method and device for assessing the viscosity of a fluid. The method and device utilize a tube with a vibrating freestanding portion into which the fluid is introduced, and relies on sensing the influence that the fluid has on the vibrational movement of the tube to assess the viscosity of the fluid. For this purpose, the freestanding portion is preferably driven at or near a resonant frequency, movement of the freestanding portion is sensed, and the viscosity of a fluid within the tube is assessed by ascertaining the damping effect the fluid has on movement of the freestanding portion at or near the resonant frequency.