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

Understanding microscale 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 solute and particle transport in and out of these pores. We present a repeatable and accessible experimental protocol developed to study the passive diffusion of a dissolved solute into microchannels with dead-end pores of rectangular as well as widening and narrowing trapezoidal geometries. Custom microchannels with pores of specified domains are produced using a rapid-prototyping technique involving inexpensive materials and a commercial craft cutter. The experimental data is compared directly to 3D numerical simulations as well as analytical solutions of a modified 1D diffusion model: the Fick-Jacobs equation. The role of pore geometry on the passive diffusion process will be highlighted. Ongoing and future directions will be discussed.