Novel multi-stage adaptive morphing of a hydrogel cube has been achieved by combining multi-metal ionoprinting and redox chemistry of iron. A demonstration of the two-stage deployment has been shown for (1) the selective opening and closing of the cube’s lid, where the hinge point has been ionoprinted with iron, and (2) the full unfolding and folding of the cube into its cruciform net, with remaining hinges ionoprinted with vanadium. The selective unfolding and folding is achieved by alternating the oxidation state of iron between +2 and +3. This is achieved using redox chemistry selective for iron. This approach could be applied, in principle, to more degrees of staging by adding additional redox responsive ionoprinted cations and appropriate selection of reducing agents.
Baker, A., Wass, D., & Trask, R. (2016). Novel Multi-Stage Three-Dimensional Deployment Employing Ionoprinting of Hydrogel Actuators. MRS Advances, 1(58), 3871-3876. https://doi.org/10.1557/adv.2016.361