Liquid Crystal Elastomer‐Based Magnetic Composite Films for Reconfigurable Shape‐Morphing Soft Miniature Machines

Abstract

Stimuli-responsive and active materials promise radical advances for many applications. In particular, soft magnetic materials offer precise, fast, and wireless actuation together with versatile functionality, while liquid crystal elastomers (LCEs) are capable of large reversible and programmable shapemorphing with high work densities in response to various environmental stimuli, e.g., temperature, light, and chemical solutions. Integrating the orthogonal stimuli-responsiveness of these two kinds of active materials could potentially enable new functionalities and future applications. Here, magnetic microparticles (MMPs) are embedded into an LCE film to take the respective advantages of both materials without compromising their independent stimuli-responsiveness. This composite material enables reconfigurable magnetic soft miniature machines that can self-adapt to a changing environment. In particular, a miniature soft robot that can autonomously alter its locomotion mode when it moves from air to hot liquid, a vine-like filament that can sense and twine around a support, and a light-switchable magnetic spring are demonstrated. The integration of LCEs and MMPs into monolithic structures introduces a new dimension in the design of soft machines and thus greatly enhances their use in applications in complex environments, especially for miniature soft robots, which are self-adaptable to environmental changes while being remotely controllable.

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

“…The fully uncoupled inputs offer additional DoFs in activating distinct parts of the material to achieve different functionalities. In contrast to the monolithic approach reported earlier, [ 47 ] this bimorph material exceeds in material heterogeneity and local addressability within a single device. These advantages of the bimorph material make it a promising candidate for future multifunctional actuators and sensors in diverse real‐world applications.…”

“…Alternatively, the monolithic approach represents a homogenous way of adding magnetic responsiveness to LCEs. [ 47 ] But the monolithic material lacks anisotropy in terms of material properties due to the uniform distribution of the MMPs. Moreover, the concentration of MMPs is limited because an excessive presence of MMPs will hinder the director field of LCEs and impair its stimuli‐responsiveness.…”

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].…”

Composites of functional polymers: Toward physical intelligence using flexible and soft materials

“…The thermal energy from the bath induced a shape change, and the composite form a helical shape. The composite could then swim upward or downward after the magnetic field was modified [39]. This example of physical intelligence represents an important step towards adaptability to local environments.…”