Tiny “galinstan” robots can run faster than a cheetah (reduced)

Scientists at Johannes Kepler University (JKU) have created flexible, steerable robots that can run, swim and jump at high speeds. In tests, the robots reached a speed of 70 BL/s (body lengths per second). These results are striking because even a cheetah (the fastest land animal on Earth) can only run up to 23 BL/s. But don’t expect absolute speed records, as the robots have millimeter-scale bodies, although these tiny machines are probably the fastest soft robots on the planet.

Soft robots are different from the conventional robots you see in factories, restaurants, and science fairs. They are constructed from flexible materials like polymers and shape memory alloys (these alloys change shape with a change in temperature). Soft materials allow robots to function similarly to a living organism (or living tissue). In contrast, conventional robots are made from rigid materials like plastic, aluminum and metal.

For a long time, scientists have tried to create soft robots fast enough to work in extreme environments where no other machine would work. Such robots could play an important role in the medical field. For example, ultra-fast robots could replace invasive methods like colonoscopy. Doctors could use fast, flexible robots to check for any abnormalities in body organs (like the stomach) that are difficult to examine with conventional diagnostic robots.

Build super-fast robots

Ultra-fast robots are made from a liquid metal alloy called galinstan. It is composed of tin (Sn), gallium (Ga) and indium (In). Galinstan is not commonly used to create soft robots; they are mostly made from silicone-based elastomers. Asked about the reason behind this, the study’s first author and soft matter physicist at JKU, Dr. Guoyong Mao, told Ars Technica: “The most important property of this material is that it is similar to a liquid at room temperature, while also having a high conductivity, which makes it useful for building flexible and deformable coils.

The researchers used liquid metal 3D printing technology to form the galinstan coils. These 3D-printed coils were then embedded in elastomer shells that hold them together with an actuator that controls their state. This produces a flexible electromagnetic coil-shaped robot (SEMR) capable of providing rapid actuation and propulsion. The researchers additionally equip the robots with L-shaped or serrated feet depending on the substrates on which they will be moving.

SEMRs are powered by lithium-polymer batteries and their ultra-fast movement is driven by electromagnetic actuators (components that convert electrical energy into mechanical energy). Actuators are magnetically responsive components and therefore fast robots can be easily controlled using a static magnetic field. In tests, tethered robots could move at 35 BL/s on a plane and 70 BL/s on a folded 3D surface. Additionally, they swam at 4.8 BL/s when tested in water. “We believe this is a new and promising technology in the field of robotics that has great potential for the future. We have not found any similar technology, using a flexible functional material, capable of performing so many tasks at such a high speed,” Mao said.

The future of ultra-fast soft robots

The researchers also performed speed tests with untethered soft robot prototypes and achieved a swimming speed of 1.8 body lengths per second (BL/s) and a maximum running speed of 2.1 BL/s. . Researchers now plan to improve the efficiency and performance of autonomous robots.

Mao and his team also say that developing more millimeter-scale SERMs using liquid 3D printing could pave the way for bigger, superfast robots in the future.

There are different types of soft robots; some could help us remove plastic waste from the oceans, and others could allow us to study the hot lunar and Martian deserts. Speed ​​is a major limiting factor for all of these soft machines. The technology behind ultra-fast SEMRs has the potential to tackle this limit.

Nature Communications, 2022. DOI: 10.1038/s41467-022-32123-4 (About DOIs)

Rupendra Brahambhatt is an experienced journalist and filmmaker. He covers scientific and cultural news and over the past five years has worked actively with some of the most innovative news agencies, magazines and media brands operating in different parts of the world.