Hydrogels have been of interest to biopharmaceutical scientists since the 60's, when Wichterle and Lim published their work on crosslinked HEMA hydrogels. Since then, common applications of hydrogels include sustained release delivery systems, biosensors and scaffolds in tissue engineering. Recently, hydrogel research has been revitalized by novel approaches in hydrogel design. Prof. Langer's group at the Massachusetts Institute of Technology has reviewed the use of microengineered hydrogels for tissue engineering applications.