Person:

Aizenberg, Joanna

The predominantly deep-sea hexactinellid sponges are known for their ability to construct remarkably complex skeletons from amorphous hydrated silica. The skeletal system from one such example, Euplectella aspergillum, consists of a square-grid-like architecture overlaid with a double set of diagonal bracings, creating a checkerboard-like pattern of open and closed cells. Here, using a combination of finite element simulations and mechanical tests on 3D-printed specimens of different lattice geometries, we show that the sponge’s diagonal reinforcement strategy achieves the highest buckling resistance for a given amount of material. Furthermore, using an evolutionary optimization algorithm, we show that our sponge-inspired lattice geometry occurs near the design space’s material distribution optimum. Our results demonstrate that lessons learned from the study of sponge skeletal systems can be exploited for the realization of square lattice geometries that are geometrically optimized to avoid global structural buckling, with implications for improved material use in modern infrastructural applications.

Dynamic crosslinking of extremely stretchable hydrogels with rapid self-healing ability is described. Using this new strategy, the obtained hydrogels are able to elongate 100 times compared to their initial length and to completely self-heal within 30 s without external energy input.

Homeostatic systems combine an ability to maintain integrity over time with an incredible capacity for interactive behavior. Fundamental to such systems are building blocks of “mini‐homeostasis”: feedback loops in which one component responds to a stimulus and another opposes the response, pushing the module to restore its original configuration. Particularly when they cross time and length scales, perturbation of these loops by external changes can generate diverse and complex phenomena. Here, it is proposed that by recognizing and implementing mini‐homeostatic modules—often composed of very different physical and chemical processes—into synthetic materials, numerous interactive behaviors can be obtained, opening avenues for designing multifunctional materials. How a variety of controlled, nontrivial material responses can be evoked from even simple versions of such synthetic feedback modules is illustrated. Moreover, random events causing seemingly random responses give insights into how one can further explore, understand and control the full interaction space. Ultimately, material fabrication and exploration of interactivity become inseparable in the rational design of such materials. Homeostasis provides a lens through which one can learn how to combine and perturb coupled processes across time and length scales to conjure up exciting behaviors for new materials that are both robust and interactive.