Until now, when scientists and engineers have developed soft robots inspired by living organisms, they have focused on living, modern-day examples. For example, we previously reported on applications of soft robotics that mimic squid, grasshoppers, and cheetahs. However, for the first time, a team of researchers has now combined the principles of soft robotics and paleontology to build a soft robotic version of a pleurocystitid, an ancient sea creature that existed 450 million years ago.
Pleurocystids are related to modern echinoderms such as starfish and brittle stars. The organism holds great importance in evolution because it is believed to be so The first echinoderms He was able to move: he used a muscular trunk to move on the sea floor. But, due to a lack of fossil evidence, scientists… Did not understand clearly How did the organism use the trunk to move underwater? “Although its life habits and posture are reasonably well understood, the mechanisms that control its trunk movement are highly controversial,” said the authors of a previously published study focusing on the trunk of echinoderms. NB.
The newly developed soft-robot replica (also called a “rhombus”) of an echinoderm has allowed researchers to decipher the organism's movement and various other mysteries associated with echinoderm evolution. In their study, they also claim that the replica will serve as a foundation for paleontology, a relatively new field that uses soft robotics and fossil evidence to explore biomechanical differences between life forms.
Make a replica of the soft robot
There are many reasons why scientists don't try to make a soft robotic version of something as extinct and as old as pleurisy. It is difficult to understand how an organism moves because there is no modern-day counterpart. In addition, fossil evidence provides only limited information about how an organism moved. For example, while some researchers suggest that pleurocystis bacteria swim, Others argue They showed rowing or sinusoidal movements.
To overcome these challenges, the researchers worked with paleontologists who specialize in echinoderms. They collected fossil images, CT scans, and all the other evidence they could find and then used this data to design the body and stem of the pleural sac. They then used elastomer molding and 3D printing to build the different parts of the robot based on the design.
When they tried to make the robot move using the torso (like a real limb), they faced another challenge. “The soft actuator uses nitinol wire, a shape memory alloy (SMA) that often burns out and becomes permanently stretched. This would require making several of stems (about 100 were made) and replaced when they go bad.
It was also difficult to replicate the soft, muscular torso of the pleurisy bacteria, as the researchers were unable to use conventional actuators, which are too bulky and rigid. “Instead, we needed to use a special 'artificial muscle' wire consisting of a nickel-titanium alloy that contracts in response to electrical stimulation. This allowed us to create a torso-like motor,” added Carmel Majidi, senior author of the study and a professor of mechanical engineering at Carnegie Mellon University. “It matches the flexibility of a natural muscular trunk.”
The researchers then ran some simulations to see how the rhombus would likely move underwater. They discovered that a longer torso led to better movement. According to the study, this was consistent with fossil evidence suggesting the evolution of longer legs in the pleura over time.
After studying the simulations, the researchers placed the robot in a 42-by-42-inch aquarium with a bottom surface similar to the sea floor. They conducted multiple tests, each lasting two minutes, to examine the robot's movement. “We demonstrate that a broad, sweeping gait can be the most efficient for these echinoderms, and that increasing trunk length may have resulted in a significant increase in speed with minimal additional energy cost.” NB In their studies.
Study of extinct animals
Making exact copies of ancient, extinct creatures using paleontology sounds interesting, but what can robots tell us that the fossil record can't? When we posed this question to Majidi, he explained that by focusing only on robots inspired by existing species, scientists may be missing out on a great opportunity to learn the biological and evolutionary principles that govern the lives of many other life forms.
For example, according to one estimate, it includes modern-day organisms Only 1 percent Of all life forms that have ever existed on Earth. “We can start to learn from the 99 percent of species that once roamed the Earth instead of just 1 percent. There are a lot of creatures that were successful for millions of years that became extinct because of drastic changes in their environment,” Majidi told Ars Technica.
Soft robotic replicas of such creatures provide paleontologists with a powerful tool to create experimental testing platforms for examining hypotheses about how these ancient life forms moved and evolved.
The current study successfully demonstrates that soft robots can be used to “revive” extinct organisms and study their locomotion and biomechanics. “This has not been done before within the soft robotics community, and we hope it will inspire more research in this area,” Desatnick added.
PNAS, 2023. DOI: 10.1073/pnas.2306580120 (About digital IDs)
Rupendra Brahambhatt is an experienced journalist and film director. He covers science and culture news, and for the past five years, he has been actively working with some of the most innovative news agencies, magazines and media brands operating in different parts of the world.
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