(142bm) Hydrogel-Filled Capillaries As in-Plane Barriers in Microfluidic Devices

Hydrogels are highly cross-linked networks of hydrophilic polymers able to absorb large quantities of water, but still retain their structure at highly hydrated states. Biopolymer hydrogels including alginate, agar, and agarose are widely used in biomedical and molecular biology applications for biological separations and as a matrix for cell support. Hydrogels have also been incorporated into microfluidic devices to develop time-dependent chemical gradients for cellular behavior studies. This research introduces a novel configuration of agarose-filled capillaries within a microfluidic device that can be used for two purposes: (i) to establish stable, reproducible, in-plane chemical gradients for diverse microfluidic applications; and (ii) to create in-plane migration barriers for cells such as microorganisms. We report protocols for preparing devices with gel confined to capillary barriers. A high-throughput optical method was used to quantify diffusivity of dyes and antibiotics through hydrogels and optical microscopy was used to characterize bacterial and protozoan motility through agarose-filled capillaries.