Modeling diffusion into dead-end pores of non-uniform cross-section

Francis, Spencer

Student Work

Modeling diffusion into dead-end pores of non-uniform cross-section

Public Deposited

The goal of this project is to develop a repeatable and accessible experimental protocol to quantify passive diffusion of solutes into microchannels with dead-end pores. Using inexpensive materials and readily accessible equipment, we produce channels with micropores with precision sufficient for microfluidic experiments. We load a pore with DI water and use a syringe pump to fill a perpendicular channel with a flourescein dye solution which slowly diffuses into the pore. We adapt the OpenFlexure microscope, a 3D-printed microscope which employs a Raspberry Pi as its core and is programmed via open-source software, to take photos of the experimental procedure. Microscope images are color-corrected using Python and then processed in Matlab to measure the gradient of concentration of dye as it penetrates into the microchannel dead-end pore thanks to molecular diffusion. The experimental method is benchmarked against a 1D model for passive diffusion of a solute into a dead-end pore of rectangular cross-section. We discuss merits and challenges of our experimental procedure and present plans for future research.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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