A butterfly’s curling feeding tube has inspired scientists to create tiny ceramic scrolls that can rapidly roll and unroll when controlled by a magnet.
The technology could eventually provide a new way to power the movements of extremely small robots.
Researchers at the University of Stuttgart and the Max Planck Institute for Solid State Research in Germany developed the microscopic devices as possible actuators—the components that produce movement in robotic systems.
Their findings were published in Advanced Materials.
Microrobots are tiny machines being developed for possible uses in medicine, manufacturing and other industries.
Scientists are also developing soft robots made from flexible materials that can safely bend, squeeze and adapt to their surroundings.
Both technologies need small, lightweight ways of producing movement. Conventional motors and mechanical parts are often unsuitable because they are too large, rigid or complicated.
To address this problem, the researchers turned to nature.
Their inspiration came from the proboscis of a butterfly, a long feeding tube that can curl into a spiral and extend when needed. Rather than copying its biological purpose, the scientists focused on its elegant rolling and unrolling movement.
The team created extremely thin films made from vanadium pentoxide, a ceramic material, and added magnetic iron oxide nanoparticles. They then gently peeled the films from a surface using a razor blade.
As the blade releases the material, it continuously bends the thin film, causing it to curl into a tightly wound microscopic scroll within seconds.
The result behaves in a surprising way for a ceramic material. Ceramics are usually thought of as hard and brittle, but these extremely thin films are flexible because of their carefully designed structure.
When a magnet approaches, the scroll rapidly unrolls. When the magnetic field is removed, it automatically curls back into its original shape. A complete cycle takes about 150 milliseconds.
Despite their tiny size, the scrolls are remarkably strong. They can lift loads more than 30 times their own weight. Tests also showed that they remained functional after 5,000 rolling and unrolling cycles.
The devices are only a few micrometers wide, while their rolled-up diameter is a few hundred micrometers. Yet when completely unrolled, they can reach lengths of up to 25 millimeters.
The researchers can also arrange multiple scrolls into programmable groups. This could allow several tiny actuators to work together to lift, transport or manipulate microscopic objects.
According to researcher Dr. Zaklina Burghard, however, the actuator itself is only part of the discovery. The manufacturing method could potentially be adapted to many other thin organic and inorganic materials.
That means the scrolling technology may eventually have applications beyond robotics. Similar structures could potentially be developed for tiny sensors, electronic components, energy-storage systems and other microscopic devices.
The research is another example of how scientists are borrowing clever designs from nature to solve engineering problems. In this case, the simple curling motion of a butterfly’s proboscis could help provide the movement needed for a future generation of tiny machines.
Source: KSR.
