From a body temperature-triggered reversible shape-memory material to high-sensitive bionic soft actuators

Plants, such as mimosa, have the ability to immediately fold inward and droop upon being touched, defending themselves from harm, and re-open a few minutes later. Bio-mimicking such a reaction in synthetic soft actuators, being able to exhibit autonomous motion driven under mild conditions, would create a new class of soft robotics. It, however, remains grand challenge, in particular in simple synthetic materials. In this work, a series of soft actuators, that can be stimulated by finger-touching, on palm, gently-blowing, or dim near-infrared (NIR) light, were fabricated via the assembly of reversible bending bilayer structure, consisting of a film of a metallo-supramolecular dynamic network and kraft paper. The reversible bending behavior of the bilayer structured material benefits from reversible shape memory effect of the synthetic polymeric material film, resulting in the converting from molecular chain movement to macroscopic autonomous motion, that is a long-sought-after and otherwise unattainable strategy. A bionic mimosa actuator was used to achieve shape-changing with a simple finger-touching, and a flowering process on palm or a breath-blowing was finished. Furthermore, mimicking the water lily, opening/closing with/without light, and the caterpillar to walk, driven by a source of low intensity-NIR light, demonstrate a range of potential applications of the fabricated soft actuator. (C) 2019 Elsevier Ltd. All rights reserved.