Characterization of the Interfacial Adhesion for Responsive Hydrogels on Substrates

In recent years a growing collection of responsive hydrogels have been developed which are capable of reversibly responding to a range of stimuli. These hydrogels operate in a hydrated environment and respond with significant volumetric reversible transformation through absorption or release of water within the polymeric network. Polymeric hydrogels in this class of shape memory materials have been successfully implemented in microfluidic and biomedical devices as components such as microchannels, micro-orifices, microvalves, micropumps and microcompressors. In practice, the hydrogel component is often polymerized on a substrate or within the confines of a channel in order to create responsive components. It is well known that the adhesion of a swelling hydrogel with its substrate varies with substrate properties. We show an experimental method to quantify the interfacial adhesion of responsive hydrogels with a substrate. This work provides a valuable method and theoretical basis for characterizing and optimizing the adhesion of responsive hydrogels.