This paper describes a student laboratory experiment to determine the molecular weight of a polymer sample by measuring the viscosity of dilute polymer solutions in a PDMS microfluidic viscometer. Sample data are given for aqueous solutions of poly(ethylene oxide) (PEO). A demonstration of shear thinning behavior using the microviscometer is described as well. The results of the implementation of the procedure with undergraduate students are also discussed.
KEY WORDS: Microfluidics, rheology, solution viscometry, image processing