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Building robots at microscopic scales creates an unusual engineering problem: even the simplest movements become difficult to produce. Conventional motors, gears and hydraulic systems cannot simply be miniaturized indefinitely, while soft robots require components that can bend and deform without breaking. Researchers therefore need new types of actuators, which are the components responsible for creating physical movement.
Researchers at the University of Stuttgart and the Max Planck Institute for Solid State Research have developed a possible solution inspired by the way a butterfly rolls and unrolls its proboscis. Their technology transforms ultrathin ceramic films into magnetically controlled microscrolls that can repeatedly extend and retract, providing a compact mechanism for moving or manipulating microscopic objects.
The microscrolls are made from thin films of vanadium pentoxide containing magnetic iron oxide nanoparticles. During manufacturing, researchers gently peel the film from its underlying surface using a razor blade. As the material is released, the blade continuously bends it, causing the film to curl into a tightly wound three-dimensional roll within seconds.
A nearby magnetic field then provides the actuation. When a magnet approaches, the embedded iron oxide nanoparticles respond to the field and the scroll rapidly unrolls. Removing the magnetic field causes the material to coil back into its original shape. This creates a reversible movement without requiring a conventional miniature motor.
Despite being ceramic, the structures do not behave like ordinary brittle ceramics. According to TechXplore, their hierarchical nano- and microstructure gives the ultrathin films enough flexibility to deform elastically while maintaining their structural integrity.
The resulting actuators are only a few micrometers wide, with coiled diameters of several hundred micrometers. When completely extended, however, they can reach lengths of up to 25 millimeters. In testing, the microscrolls continued operating after 5,000 cycles and were capable of moving loads exceeding 30 times their own weight.
Multiple scrolls can also be arranged into programmable arrays. Coordinating several actuators could allow microscopic robotic systems to lift, transport or manipulate objects rather than relying on a single moving element.
While the research is not specifically aimed at defense, the underlying technology could eventually have applications in security and aerospace systems. Micro-actuators could support extremely small robotic platforms, miniature sensing mechanisms or adaptive components designed to operate where conventional mechanical systems are impractical. Their magnetic control could also be useful when physical connections to the actuator are difficult.
The researchers emphasize that the larger breakthrough is the manufacturing method rather than one specific actuator. The scrolling technique could potentially be applied to other organic and inorganic thin films, opening possibilities beyond robotics in sensors, electronics and energy-storage devices.
By borrowing a simple movement from a butterfly, the researchers have demonstrated a new way to turn flat functional materials into programmable three-dimensional machines, without needing the motors and mechanical assemblies used by larger robots.
The research was published here.
