A differential viscosity detector for use in miniturized chemical separation systems

Abstract—In this paper, we present a micromachined differential viscosity detector suitable for integration into an on-chip hydro-dynamic chromatography system. The general design, however, is applicable to any liquid chromatography system that is used for separation of polymers. The micromachined part of the detector consists of a fluidic Wheatstone bridge and a low hydraulic capaci-tance pressure sensor of which the pressure sensing is based on op-tical detection of a membrane deflection. The stand-alone sensor shows a resolution in specific viscosity of 3 10 3, in which spe-cific viscosity is defined as the increase in viscosity by a sample, relative to the baseline viscosity of a solvent. [0947] Index Terms—Microfluidics, viscometer, viscosity detection