Reversible Snapping of Constrained Anisotropic Hydrogels Upon Light Stimulations.

Creatures, such as Venus flytrap and hummingbirds, capable of rapid predation through snap-through transition, provide paradigms for the design of soft actuators and robots with fast actions. However, these artificial "snappers" usually need contact stimulations to trigger the flipping. Reported here is a constrained anisotropic poly(N-isopropylacrylamide) hydrogel showing fast snapping upon light stimulation.

Animating hydrogel knotbots with topology-invoked self-regulation.

Steering soft robots in a self-regulated manner remains a grand challenge, which often requires continuous symmetry breaking and recovery steps for persistent motion. Although structural morphology is found significant for robotic functions, geometric topology has rarely been considered and appreciated. Here we demonstrate a series of knotbots, namely hydrogel-based robots with knotted structures, capable of autonomous rolling and spinning/rotating motions.

Fabricating defogging metasurfaces a water-based colloidal route.

Metamaterials possess exotic properties that do not occur in nature and have attracted significant attention in research and engineering. Two decades ago, the field of metamaterials emerged from linear electromagnetism, and today it encompasses a wide range of aspects related to solid matter, including electromagnetic and optical, mechanical and acoustic, as well as unusual thermal or mass transport phenomena. Combining different material properties can lead to emergent synergistic functions applicable in everyday life.

Magneto-Orientation of Magnetic Double Stacks for Patterned Anisotropic Hydrogels with Multiple Responses and Modulable Motions.

Reported here is a multi-response anisotropic poly(N-isopropylacrylamide) hydrogel developed by using a rotating magnetic field to align magnetic double stacks (MDSs) that are fixed by polymerization. The magneto-orientation of MDSs originates from the unique structure with γ-Fe O nanoparticles sandwiched by two silicate nanosheets. The resultant gels not only exhibit anisotropic optical and mechanical properties but also show anisotropic responses to temperature and light.

Patterned Electrode Assisted One-Step Fabrication of Biomimetic Morphing Hydrogels with Sophisticated Anisotropic Structures.

Anisotropic structures are ubiquitous in nature, affording fascinating morphing behaviors. Biomimetic morphing materials can be developed by spatially controlling the orientations of molecules or nanofillers that produce anisotropic responses and internal stresses under external stimuli. However, it remains a serious challenge to fabricate materials with sophisticated anisotropic architectures.