Small-Molecule Diffusion through a Hydrogel in a Microfluidic Device

Andrew Litzenberger, Chemical Engineering, Bucknell University, 701 Moore ave C1454, Lewisberg, PA 17837

Hydrogels are used extensively in the biomedical industry because of their biocompatibility properties. The unique structure of a hydrogel can affect the diffusion process. The diffusion of particles through a hydrogel's cross-linked polymer structure swollen in an aqueous environment is relevant to applications such as drug delivery and modeling transport in parts of the human body. Interactions between the diffusive species and the hydrogel network are studied in a homogenous environment (semi-infinite slab) at the hydrogel-water boundary in a microfluidic device.

Closed-face microfluidic devices are fabricated using photolithography. The hydrogels are characterized by their equilibrium water content. Unsteady diffusion within the microfluidic device is monitored and recorded using a digital microscope. The information is analyzed with techniques drawn from digital microscopy and image analysis, and a diffusion coefficient is obtained.

These diffusion coefficients are related to those obtained from NMR analysis.