AN OPTICAL MICRO-FLUIDIC VISCOMETER

Abstract

A new method for measuring viscosity relative to a reference fluid and applicable to a continuous process micro-fluidic device is presented. The measurement is based on the volume flow rate ratio and interface location between two co-flowing streams in a micro-fabricated T-channel and utilizes the inversion of a closed-form solution for the velocity distribution in a rectangular channel. Neither absolute flow rates or pressure differences are required. Since optical detection is the basis for the measurement, the method lends itself to the measurement of intrinsic viscosity, which requires measurement of both absolute viscosity and concentration. Experimental verification of the method yielded measurements of absolute viscosity within two percent of standard methods for dilute aqueous dextran suspensions.