We probably all killed spider What if that arthropod’s corpse could be turned into something useful? Researchers at Rice University in Texas think they can and are pioneering the field of “necrorobics” by injecting air into dead spiders to use them to grasp small objects.
While Rice University assistant professor of mechanical engineering Daniel Preston 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 curled up. It turns out that spiders extend their legs using hydraulic pressure from fluid pumped into their legs from a central cavity, meaning their legs are permanently retracted when they die. Preston and Yap wondered if they could break this hydraulic process by injecting air into a dead spider’s legs, forcing them to open. They found what they could, and their work was published on this terrifying opportunity to make a biological trap. Advanced Science On Monday.
“[Spiders] they actually only have flexing muscles,” Yap said in a video call, meaning spiders can pull their legs in, but they don’t have the muscles to extend them. “The way to stretch your legs is to use hydraulic pressure.”
This pressure comes from the spider’s prosoma (the spider’s cephalothorax, where its legs attach to its body); this allows the arachnid to walk by sending fluid to its legs; individual legs are controlled by the opening and closing of valves in the spider’s anatomy. Preston, Yap, and colleagues found that if they carefully inserted a syringe into the prosoma of a dead spider, they could extend and retract all of the spider’s legs simultaneously, mimicking air and hydraulic pressure. This meant that the spider could be used as a scavenger. But why are you attempting something so disturbing?
“We’re interested in using them for things like sample collection,” Preston said. “They have an inherent cohesion because of this hydraulic or pneumatic actuation that we can apply, and this helps protect fragile specimens and even other live insects, if we want to collect them in the field, for example.”
The features of the redesigned arthropods are incredibly promising: The team has found that a spider gripper can withstand 1000 on/off cycles and be used to lift 130% of its own body weight.
The researchers mostly used wolf spiders for the study in this particular manuscript, but they believe other spider species could be used as well. Interestingly, Yap said the group found that spiders with larger body mass, such as the Goliath spider, can lift objects that are only 1/10 of their body weight, while smaller spiders — such as jumping spiders. twice its body weight.
As for how those outside the lab reacted to the project, Preston says many were supportive and even excited when they saw how effective the gripper was. Still, others weren’t too happy with the spiders around.
“An employee of our front office doesn’t like spiders very much. So we had to call the front desk when another delivery arrived for us to use for the project, and we kind of let them know,” Preston said with a chuckle. The team ordered their spider from a biological supply company, but unfortunately some of them didn’t die. “They’re lifeless, but sometimes we have to euthanize them, so we search through literature for the most humane way to kill them.”
While the project may seem bizarre, Preston believes his lab fits perfectly within the scope of soft robotics research. “We’re looking at everything at the intersection of energy, materials, and fluids,” he says. “Soft robotics typically apply non-traditional materials, things that aren’t typical hard plastic metals, but instead things like hydrogels and elastomers, and unique operating modes like magnetism and light.” Preston and Yap are very interested in using this as a starting point for other research on necrobotic grippers, such as figuring out how to open and close individual legs.
While researchers around the world were working on bio-inspired robotics, Preston, Yap and the rest of the team got into the chase and used biology itself plucked from the floor of their lab. This creative, nature-inspired work is clearly crazy science at its best.
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