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.