Scientists use dead spiders as gruesome claw catchers

We’ve probably all killed one spider or two in the past, but what if that arachnid’s corpse could be repurposed into something useful? Well, researchers at Rice University in Texas think it’s possible and are pioneering the field of “necrobotics” by injecting air into dead spiders to use them to grab small objects.

When Daniel Preston, an assistant professor of mechanical engineering at Rice University, was setting up his lab, he and graduate student Faye Yap wondered why a dead spider in the corner of the room had its legs rolled up. It turns out that spiders extend their legs using hydraulic pressure, which comes from fluid pumped into their legs from a central cavity, which means that when they die, their legs permanently retract . Preston and Yap wondered if they could hack this hydraulic process by blowing air into a dead spider’s legs to force them open. They found they could, and their study of this macabre opportunity to make a biological gripper was published in Advanced sciences In Monday.

“[Spiders] actually only have flexing muscles,” Yap said in a video call, which means spiders can retract their legs, but have no muscles to extend them. “The way they extend their legs uses hydraulic pressure.”

This pressure comes from the spider’s prosoma – the spider’s cephalothorax, where its legs attach to its body – which sends fluid to the arachnid’s legs, allowing it to walk – the individual legs are controlled by the opening and closing of valves in spider anatomy. Preston, Yap and their colleagues found that if they carefully inserted a syringe into the prosoma of a dead spider, they could mimic hydraulic pressure with air, extending and retracting all of the spider’s legs at the same time. . This meant the spider could be used as a claw. But why attempt something so disturbing?

“We’re interested in using them for things like collecting samples,” Preston said. “They have an intrinsic compliance due to this hydraulic or pneumatic actuation that we are able to apply, and which makes it possible to protect fragile samples or even other living insects, for example, if we wanted to collect them in the field.

The properties of the repurposed arachnid are incredibly promising: the team found that a spider claw could last up to 1,000 open/close cycles and could be used to lift 130% of its own body weight.

The researchers primarily used wolf spiders for work in this particular manuscript, but they believe other spider species could also be used. Interestingly, Yap says the group found that spiders with larger body mass, like the Goliath spider, were only able to lift objects that weighed 1/10th of their body weight, while spiders with more small ones, like jumping spiders, could be able to lift as much as twice their body weight.

As for how people outside the lab reacted to the project, Preston says most were supportive and even excited when they saw how effective the gripper was. Others, however, weren’t too happy to have spiders around.

One of the employees who works in our front office really doesn’t like spiders. So we had to call the front office every time we had another delivery to use for the project and just give them a whim,” Preston said with a chuckle. The team ordered their spiders from a biological supply company, but unfortunately some of them did not die. Yap clarified: “Sometimes they are inanimate, but sometimes we have to euthanize them. So we look for the most humane way to kill them in literature.

Although the project may seem bizarre, Preston thinks it fits perfectly into his lab’s field of research in the study of soft robotics. “We look at everything at the intersection of energy, materials and fluids,” he says. “Soft robotics typically applies non-traditional materials, things that aren’t the typical hard plastic metals, but rather things like hydrogels and elastomers and unique modes of actuation like magnetism and light.” Preston and Yap are very interested in using this as a starting point for further research into necrobotic claws, such as figuring out how to open and close individual legs.

As researchers around the world work on bio-inspired robotics, Preston, Yap and the rest of the team cut to the chase and used biology itself, ripped from the floor of their lab. This creative work inspired by nature is clearly mad science at its best.

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