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The Isermann Department of Chemical and Biological Engineering at Rensselaer Polytechnic Institute has developed a Microfluidics laboratory experiment to introduce undergraduate chemical engineers to this new and upcoming field and to reinforce some basic concepts from transport and interfacial phenomena.
The two-part experiment is designed to demonstrate Taylor-dispersion and its effects on mixing and reaction and the determination of surface tension by measuring the rate of droplet formation in a microchannel. Two different types of microchannels are used and both were purchased from Micronit.
The Taylor-dispersion experiment sends pulses of dyes through a continuously running stream down a channel. Pulse-width detection is done using an optical fiber-based spectrophotometer. Once the dispersion coëfficient and solute diffusivity are determined, a second experiment is run where the dye is bleached. Numerical simulation of the process is compared with data from the experiment. Micronit's standard R150.332.2 microreactor chip was found to be optimal for this experiment because of its long channel length (>30cm) which facilitated observing the axial dispersion phenomenon. The droplet formation experiment was carried out in the standard FC_X3550.CH2 chip. Conveniently, the symmetric channel inlet design provided effortless pressure control to vary the shearing rates of the two immiscible fluids used in the experiment, toluene and water. In this experiment, droplets are observed either visually, using a microscope or spectrophotometrically, by incorporating a water insoluble dye into the dispersed phase.
The Y-shaped junction of the R150.332.2 chip used for the Taylor-dispersion experiment
Our institution is pleased with the overall quality provided by Micronit. Other educational establishments could benefit from the use of Micronit's products to create experiments for their own student laboratory classes.
More information on Micronit's microfluidics products can be found here.
Joel L. Plawsky, Ph.D.
Professor of Chemical Engineering
Rensselaer Polytechnic Institute
Isermann Department of Chemical and Biological Engineering
www.rpi.edu
plawsky@rpi.edu
David Amirbekyan
B.S. Chemical Engineering
Rensselaer Polytechnic Institute
Brendan Levesque
B.S. Chemical Engineering
Rensselaer Polytechnic Institute