Diffusion into dead-end pores of non-uniform cross-sections

Understanding micron-scale fluid flows is critical to perfecting the manufacturing and use of microfluidic technologies for medical and engineering applications. Microchannels with dead-end pores are ubiquitous in natural and industrial settings, and ongoing research focuses on fluid and chemical transport in and out of these pores. In the present work, we detail a repeatable and accessible experimental protocol developed to study the passive diffusion of a dissolved solute into dead-end pores of rectangular and trapezoidal geometries. Custom microchannels with pores of specified geometries are rapidly produced using inexpensive materials and a commercial craft cutter. The experimental data is compared directly to both detailed 3D numerical simulations as well as analytical solutions of an effective 1D diffusion equation: the Fick-Jacobs equation. The role of the pore geometry on the passive diffusion process will be highlighted. Ongoing and future directions will be discussed.