Hydrogels are 3-D polymeric networks that can absorb large amounts of water while maintaining their structure. They are made up of hydrophilic polymers that are crosslinked to form a network that can swell in water but not dissolve. Hydrogels have many potential biomedical applications such as drug delivery, tissue engineering, wound healing, and biosensors. Designing a hydrogel for biomedical use involves carefully selecting polymers, crosslinking methods, functionalization, shape, degradation properties, biocompatibility, and sterilization.