Modeling bio-inspired morphing mechanisms in hydrogel micro capsules*

We study changes in shape and size triggered by external stimuli in structures made of soft active materials. In particular, we consider morphing mechanisms driven by hydration and dehydration processes in capsule-like bodies which can hydrate and dehydrate causing the lateral collapse of the capsule body and the change of shape of the capsule. Typical examples come from Nature. In fern sporangium, the cells in the crest to one side of a spherical capsule enclosing the spores lose water by evaporation, so determining tension building up within them, and lateral walls collapsing internally [1,2]. In Sphagnum Moss, dehydration of the capsules cause them to change shape from spherical to cylindrical and to increase the internal air pressure [3].

In both the examples, the coupling between the dehydration process and the change in internal pressure determines a fast mechanism which allows to realize spore dispersal.

The goal of our study is to identify the mechanical determinants of the mechanism and investigate the role of the key geometrical and material parameters.


[1] X. Noblin et al., Science, 2012, 335, 1322.
[2] M. Curatolo et al., Soft Matter 14, 2310–2321, 2018.
[3] Dwight L. Whitake and Joan Edwards, Science, 329, 2010