Diffusion-driven stress relaxation of gels under incremental planar extensions

We investigated the stress response of hydrogels to multiple and consecutive planar extensions using the standard Flory-Rehner thermodynamics. We show explicitly how the stress relaxation at a given extension depends on both the number and magnitude of incremental steps that lead to such extension. These results have the potential to impact the design of hydrogel-based actuators where a prescribed extension can be achieved through several consecutive extensions.