© Mickaël CASTRO/Antoine LE DUIGOU/IRDL/CNRS Images
Bio-composite strips reproducing the natural movements of the pine cone, which opens and closes according to ambient humidity. These biomaterials, based on flax fibre, are immersed in water to observe their opening, which is reversible, on contact with moisture. Pine cones are in fact natural hygromorphic actuators. The bi-layered structure of the scales is the source of this movement. On contact with moisture, a twist is produced by the hygroscopic deformation resulting from differential swelling between the two layers. This experimentation is undertaken with a bio-inspired approach. Dynamic cladding or solar tracker applications can now be considered.