Wirelessly Actuated Thermo‐ and Magneto‐Responsive Soft Bimorph Materials with Programmable Shape‐Morphing

Abstract

Soft materials that respond to wireless external stimuli are referred to as “smart” materials due to their promising potential in real‐world actuation and sensing applications in robotics, microfluidics, and bioengineering. Recent years have witnessed a burst of these stimuli‐responsive materials and their preliminary applications. However, their further advancement demands more versatility, configurability, and adaptability to deliver their promised benefits. Here, a dual‐stimuli‐responsive soft bimorph material with three configurations that enable complex programmable 3D shape‐morphing is presented. The material consists of liquid crystal elastomers (LCEs) and magnetic‐responsive elastomers (MREs) via facile fabrication that orthogonally integrates their respective stimuli‐responsiveness without detrimentally altering their properties. The material offers an unprecedented wide design space and abundant degree‐of‐freedoms (DoFs) due to the LCE's programmable director field, the MRE's programmable magnetization profile, and diverse geometric configurations. It responds to wireless stimuli of the controlled magnetic field and environmental temperature. Its dual‐responsiveness allows the independent control of different DoFs for complex shape‐morphing behaviors with anisotropic material properties. A diverse set of in situ reconfigurable shape‐morphing and an environment‐aware untethered miniature 12‐legged robot capable of locomotion and self‐gripping are demonstrated. Such material can provide solutions for the development of future soft robotic and other functional devices.

Bistable and Multistable Actuators for Soft Robots: Structures, Materials, and Functionalities

“…They could achieve multi-mode locomotion to tackle with complex scenarios, [73,256] including crawling, running, climbing, and jumping over obstacles, and swimming, with an in situ tunable locomotion speed by switching between monostable, bistable, and multistable mode or manipulating the energy barrier for actuation. To achieve the multimodal locomotion in different scenarios, dual or multi-actuation [191,215] will be beneficial to overcome the different energy barriers, for example, dual thermal/photothermal and magnetic actuation in soft active materials such as LCPs [257] and hydrogels. To enhance the maneuverability, untethered bistable or multistable soft robots are highly needed by either integrating onboard control and power systems or utilizing the remote stimuli-responsive materials that are responsive to environmental temperature, light, and/or magnetic field in a controlled way.…”

Programmable Light‐Driven Liquid Crystal Elastomer Kirigami with Controlled Molecular Orientations

“…1D locomotion has been demonstrated in LCE films [53,54] and LCE with the help of frames, [33] ratcheted surface, [55][56][57] or attached magnetic legs. [58] Recently, multidirectional locomotion is demonstrated by gluing three-wavelength modulated double-layer LCE films [59] or by using an external structure of plastic tube in a specially designed LCE kirigami. [37] Despite these successes, locomotion with arbitrary directions in a monolithic LCE film without external structures remains a central challenge.…”

Evolving from Laboratory Toys towards Life-Savers: Small-Scale Magnetic Robotic Systems with Medical Imaging Modalities

“…Not willing to forsake the aforementioned convenience, researchers have been trying to maintain such a direct line-of-sight in as many cases as possible. Many experiments, especially the preliminary ones, of small-scale magnetic robots are performed in air [35][36][37][38], at an interface [39][40][41][42][43][44][45], or in an aqueous medium inside a transparent container, such as a Petri dish, a beaker, or a tube [32,[46][47][48][49][50][51][52][53][54][55]. For example, Tasoglu et al used an untethered magnetic microrobot to code three-dimensional (3D) materials with tunable structural, morphological, and chemical features [26].…”