Determination of hydrogel swelling factors by two established and a novel non-contact continuous method

Hydrogels were introduced as suitable materials for applications in, e.g., medical, agriculture, or daily life areas. Swelling characteristics of a hydrogel are important and must be precisely known for various fields of application. In medicine, where hydrogels are used as implants or drug delivery systems, precise knowledge of the swelling behavior is essential. Especially in ophthalmology as part of cataract surgery, the visco-elastic properties of the hydrogels could even allow for the restoration of accommodation. The easiest way to describe the swelling is by measuring the swelling ratio, generally done by scaling. Besides that, it can also be done by volume investigations. The similarities and differences are studied on five hydrogel samples made of methyl methacrylate and N-vinyl pyrrolidone. Additionally, a first camera-based approach, potentially providing an automated, quasi-continuous non-contact method for swelling kinetics investigations, is described.