(opens in a new tab)
Taking the lifeless body of a dead spider and reanimating it as a robot is an idea that would give most people nightmares. But scientists aren’t most people. Recently, a team of researchers returned the corpses of wolf spiders in arcade-style claw machines that could pick up and move a variety of objects, including other dead wolf spiders.
The idea for mechanized arachnid claws, or “necrobots,” originated when researchers noticed a dead spider curled up in a ball in a corner of their engineering lab. After researching why the legs of dead spiders always seem to be pulled firmly towards their abdomens, scientists learned that the spiders’ joints were controlled by a hydraulic pressure system that fails when the arachnids die. The team then realized that they could reverse engineer this hydraulic system to hijack the spider’s corpse and give it a second life as a machine.
By blowing air into wolf spider corpses, the team discovered that all eight legs could be simultaneously straightened and curled up to create a grabbing motion that could then be used to lift objects. Wolf spiders – a group that includes nearly 2,400 species in the family Lycosidae – can carry objects much larger than themselves and have tiny hairs on their legs that give them extra grip. This means Necrobots could pick up a wide variety of items, including tricky ones electric components, oddly shaped meshes and, yes, dead wolf spiders, researchers have explained in a new study.
The researchers believe their work could inspire the creation of other Necrobots from the corpses or individual body parts of other dead animals. “This is something that hasn’t been used before, but has a lot of potential,” said the study’s lead author, Daniel Preston, an assistant professor of mechanical engineering at Rice University in Houston. said in a press release (opens in a new tab).
Related: Millions of Palm-Sized Flying Spiders Could Invade the East Coast, Scientists Say
In humans and other vertebrates (animals with spines), most joints are controlled by pairs of antagonistic muscles, which are opposing muscles that pull a joint in different directions. An example of a pair of antagonistic muscles in humans is the biceps and triceps: when the biceps contracts and the triceps relaxes, our arm bends at the elbow; when the triceps contracts and the biceps relaxes, our arm straightens again.
However, spiders only have one flexor muscle in their joints that allows them to bend their legs. To straighten their legs again, spiders use a hydraulic pressure system, which involves forcing blood from a chamber near the thorax, known as the prosoma, into the legs. The blood acts as the antagonist of the sole flexor muscle and pushes the joint backward. But when the spider dies, there is nothing to push against that muscle and the joints close.
(opens in a new tab)
“When they die, they lose the ability to actively pressurize their bodies,” study lead author Faye Yap, a mechanical engineering doctoral student at Rice University, said in the statement. “That’s why they cower.”
To transform wolf spiders into necrobots, the researchers recreated the hydraulic system of arachnids, substituting air for blood. The team inserted a needle into the prosoma of a desiccated spider corpse and glued it in place. When they blew air into the chamber through the needle, the airflow activated the hydraulic system like a spider’s blood would, forcing the legs to straighten. When the air was drawn in through the needle, the legs returned to their naturally curled up position.
Normally, spiders control each leg through valves that adjust blood flow to each limb. The researchers were concerned about how this would affect the mobility of their reanimated spiders, as there was no easy way to open the valves in the corpses’ legs. But it turned out that in the dead spiders, the valves were permanently stuck in the “open” position, Preston said. This allowed researchers to simultaneously control all of a necrobot’s legs, making them perfect for grabbing objects, he added.
(opens in a new tab)
The dead wolf spiders were so well suited to their new task that the researchers were able to create a working necrobot on their first attempt. “We took the spider, we put the needle in there not knowing what was going to happen,” Yap said. “And when we did, it worked the first time, right off the bat.” It is extremely rare for engineers to succeed so quickly during this type of trial-and-error experiment, she added.
Further experiments with the Necrobots showed that they could reliably lift objects weighing over 130% of their own body weight, and sometimes they could lift even more. However, after around 1,000 cycles of opening and closing their legs, the Necrobots became less efficient and showed signs of damage.
“We think it’s related to joint dehydration issues,” Preston said. However, the researchers think they can eventually overcome this problem by coating the legs with special polymers, which would extend the life of the necrobots, he added.
Necrobots have a wide range of potential applications, according to the release. The team has previously shown that spider grippers can be used to move fragile components in electrical circuits without damaging them, hinting at their usefulness in aiding microelectronics assembly and other small-scale construction projects. . And if scientists can replicate their work with other species, it could further expand the range of projects that could benefit from a Necrobot’s delicate touch, the team reported in the study.
(opens in a new tab)
Conservationists could also use necrobots to collect live insects to study in the wild without harming them, Yap said. The reanimated spiders are likely to be very effective tools for catching insects because their legs have evolved specifically to catch tiny arthropods, and their natural camouflage could help keep them hidden in the field, she added.
Using Necrobots instead of metal and plastic mechanical constructs could also help reduce the waste produced when crafting tools. “Spiders themselves are biodegradable,” Preston said. “So we’re not introducing a big waste stream, which can be a problem with more traditional components.”
Wolf spiders are extremely common, widespread, and easy to collect, so there would be a cheap and plentiful supply of spider corpses for engineers to turn into necrobots – as long as those engineers aren’t. arachnophobeThis is.
The study was published online July 25 in the journal Advanced sciences (opens in a new tab).
Originally posted on Live Science.