Magneto‐Thermomechanically Reprogrammable Mechanical Metamaterials

Abstract

Future active metamaterials for reconfigurable structural applications require fast, untethered, reversible, and reprogrammable (multimodal) transformability with shape locking. Magnetic control has a superior advantage for fast and remotely controlled deployment; however, a significant drawback is needed to maintain the magnetic force to hold the transformation, limiting its use in structural applications. The shape‐locking property of shape‐memory polymers (SMPs) can resolve this issue. However, the intrinsic irreversibility of SMPs may limit their reconfigurability as active metamaterials. Moreover, to date, reprogrammable methods have required high power with laser and arc welding proving to be energy‐inefficient control methods. In this work, a magneto‐thermomechanical tool is constructed and demonstrated, which enables a single material system to transform with untethered, reversible, low‐powered reprogrammable deformations, and shape locking via the application of magneto‐thermomechanically triggered prestress on the SMP and structural instability with asymmetric magnetic torque. The mutual assistance of two physics concepts—magnetic control combined with the thermomechanical behavior of SMPs is demonstrated, without requiring new materials synthesis and high‐power energy for reprogramming. This approach can open a new path of active metamaterials, flexible yet stiff soft robots, multimodal morphing structures, and mechanical computing devices where it can be designed in reversible and reprogrammable ways.

Flexible nanomechanical bit based on few-layer graphene

“…Furthermore, the strain engineering for the nanomechanical bit to transit between states '0' and '1' is also feasible in the experiment. [40][41][42][43][44][45] Furthermore, it is important to note that these states are reversible without needing further energy input, as is commonly the case for mechanical bits based on bistable configurations, 46,47 i.e. that the stretched TLG in the state '1' will return back to the initial state '0', when the tensile mechanical strain is removed.…”

Hard magnetics and soft materials—a synergy

“…The magnitude and direction of the magnetic field can be controlled to precisely manipulate the shape-morphing behavior of the material. Shape-morphing structures based on hMSMs have several potential applications [105,505,506]. They can be used in adaptive and reconfigurable devices such as soft robotics, where the ability to change shape enables versatile and customized movements.…”

Advances in autonomous materials and structures

“…This system could be fined-tuned to improve the efficiency without structural reconstruction. Zou et al [55] proposed a magneto-thermomechanical mechanical metamaterial with low-powered re-programmability. The proposed work opens a new path to design computing devices in reversible and reprogrammable ways.…”