HOUSTON – Engineers at Rice University repurposed dead spiders as mechanical grippers.
“It happens to be the case that the spider, after it’s deceased, is the perfect architecture for small scale, naturally-derived grippers,” said Daniel Preston, a mechanical engineer with Rice’s George R. Brown School of Engineering.
Rice said in a news release on July 25 that Preston’s lab specializes in soft robotic systems that use nontraditional materials, rather than hard plastics, metals and electronics. These nontraditional materials include elastomers, hydrogels...and now apparently spiders.”
“This area of soft robotics is a lot of fun because we get to use previously untapped types of actuation and materials,” Preston said. “The spider falls into this line of inquiry. It’s something that hasn’t been used before but has a lot of potential.”
A study published in Advanced Science outlines how Preston and Rice graduate student Faye Yap “used a spider’s physiology in a first step toward a novel area of research they call ‘necrobotics,’” Rice shared in news release.
They got the idea after coming across a dead spider.
“We were moving stuff around in the lab and we noticed a curled up spider at the edge of the hallway,” she said. “We were really curious as to why spiders curl up after they die.”
A quick search and they found their answer: “Spiders do not have antagonistic muscle pairs, like biceps and triceps in humans,” Yap said. “They only have flexor muscles, which allow their legs to curl in, and they extend them outward by hydraulic pressure. When they die, they lose the ability to actively pressurize their bodies. That’s why they curl up.”
“At the time, we were thinking, ‘Oh, this is super interesting.’ We wanted to find a way to leverage this mechanism,” she said.
So, naturally, they got a dead spider, punctured it with a syringe and puffed air into it so they could curl and unfurl its limbs.
“When we did it, it worked, the first time, right off the bat actually,” Yap said in a video demonstration. “I don’t even know how to describe it -- that moment when you see it move.”
Preston said he envisions several uses for the “necrobotic” spiders.
“There are a lot of pick-and-place tasks we could look into, repetitive tasks like sorting or moving objects around at these small scales, and maybe even things like assembly of microelectronics,” he said.
“Another application could be deploying it to capture smaller insects in nature, because it’s inherently camouflaged,” Yap said.
The team ran one spider through 1,000 open-close cycles to test how durable its limbs were. Their finding -- the legs were fairly robust.
“It starts to experience some wear and tear as we get close to 1,000 cycles,” Preston said. “We think that’s related to issues with dehydration of the joints. We think we can overcome that by applying polymeric coatings.”
So, why use dead spiders as “corpse claw machines”? They’re better for the environment.
“The spiders themselves are biodegradable,” Preston said. “So we’re not introducing a big waste stream, which can be a problem with more traditional components.”
The experiment unnerved some arachnophobes on the internet.
“Thank you for unlocking a new fear,” wrote one YouTube commenter.
“I’ve watched enough B-Horror, and I don’t like how this is going,” wrote another.
Preston and Yap reassured people that though their experiments look like the stuff of nightmares they’re not reanimating spiders.
“Despite looking like it might have come back to life, we’re certain that it’s inanimate, and we’re using it in this case strictly as a material derived from a once-living spider,” Preston said. “It’s providing us with something really useful.”