Millirobots that can adapt to unstructured environments, operate in confined spaces, and interact with a diverse range of objects would be desirable for exploration and biomedical applications. The continued development of millirobots, however, requires simple and scalable fabrication techniques. Here, we propose a minimalist approach to construct millirobots by coating inanimate objects with a composited agglutinate magnetic spray. Our approach enables a variety of one-dimensional (1D), 2D, or 3D objects to be covered with a thin magnetically drivable film (~100 to 250 micrometers in thickness). The film is thin enough to preserve the original size, morphology, and structure of the objects while providing actuation of up to hundreds of times its own weight. Under the actuation of a magnetic field, our millirobots are able to demonstrate a range of locomotive abilities: crawling, walking, and rolling. Moreover, we can reprogram and disintegrate the magnetic film on our millirobots on demand. We leverage these abilities to demonstrate biomedical applications, including catheter navigation and drug delivery.
The Pt–Cu single-atom alloy (SAA) catalyst showed significantly enhanced activity, selectivity, and stability for the hydrogenolysis of methyl glycolate to ethanol.
Carbon‐based materials are widely used as light‐driven soft actuators relying on their thermal desorption or expansion. However, applying a passive layer in such film construction greatly limits the actuating efficiency, e.g., bending amplitude and speed. In this work, a dual active layer strengthened bilayer composite film made of graphene oxide (GO)–polydopamine (PDA)–gold nanoparticles (Au NPs)/polydimethylsiloxane (PDMS) is developed. In this film, the conventional passive layer is replaced by another AuNPs‐enhanced thermal responsive layer. When applying NIR light exposure, the whole film deforms controllably resulting from the water loss in the GO–PDA–Au NPs layer and thermal expansion in the PDMS layer. Benefiting from the dual active bilayer mechanism, the thin film's actuating efficiency is dramatically improved compared with that of conventional methods. Specifically, the bending amplitude is enhanced up to 173%, and the actuating speed is improved to 3.5‐fold. The soft actuator can act as an artificial arm with high actuating strength and can be used as a wireless gripper. Moreover, the film can be designed as soft robots with various locomotion modes including linear, rolling, and steering motions. The developed composite film offers new opportunities for biomimetic soft robotics as well as future applications.
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