Hydrogel Properties and Characterization Techniques

The unique structure of hydrogels as materials, including their soft mechanical properties, their typically high water contents, their capacity to respond to changes in their solvent environment, and their tunable and often multi-scale porosity, offers both significant challenges and specific opportunities in terms of their characterization. Herein, we describe the key properties associated with hydrogels (from both qualitative and quantitative perspectives) and review the major analytical techniques used to probe those properties, highlighting the strengths and weaknesses of various available strategies. Chemical, physical, and biological properties are all reviewed, with an emphasis on the techniques developed specific to hydrogels to measure swelling, mechanics, gelation time, and porosity.