Multilayer microfluidic PEGDA hydrogels.

Development of robust 3D tissue analogs in vitro is limited by passive, diffusional mass transport. Perfused microfluidic tissue engineering scaffolds hold the promise to improve mass transport limitations and promote the development of complex, metabolically dense, and clinically relevant tissues. We report a simple and robust multilayer replica molding technique in which poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) diacrylate (PEGDA) are serially replica molded to develop microfluidic PEGDA hydrogel networks embedded within independently fabricated PDMS housings. We demonstrate the ability to control solute-scaffold effective diffusivity as a function of solute molecular weight and hydrogel concentration. Within cell laden microfluidic hydrogels, we demonstrate increased cellular viability in perfused hydrogel systems compared to static controls. We observed a significant increase in cell viability at all time points greater than zero at distances up to 1 mm from the perfused channel. Knowledge of spatiotemporal mass transport and cell viability gradients provides useful engineering design parameters necessary to maximize overall scaffold viability and metabolic density. This work has applications in the development of hydrogels as in vitro diagnostics and ultimately as regenerative medicine based therapeutics.