When graduate student in mechanical engineering Faye Yap noticed a dead spider curled up in the corridor, she had the strange idea that it would be used as a robotics component.
Some people’s worst scenario may involve turning dead spiders into mechanical grippers, yet it might have real advantages. Spider legs are able to gently and securely grasp huge, delicate, and asymmetrically shaped objects without damaging them.
Therefore, Yap and her colleagues at Rice University developed a method to make a dead wolf spider’s legs unfold and grab onto objects in partnership with mechanical engineer Daniel Preston.
They gave this new branch of robotics the name “necrobotics.”
Strangely, spider legs are not extended by muscles but rather by hydraulic pressure. When the prosoma chamber, also known as the cephalothorax, contracts, inner body fluid is forced into the legs, causing them to lengthen.
So, using a glob of superglue, the scientists sealed the needle’s tip after inserting it into the spider’s prosoma chamber. The spider’s legs could be made to go through their whole range of motion in less than a second by just inflating the syringe with a tiny puff of air.
“We took the spider, we placed the needle in it not knowing what was going to happen,” says Yap in a video on the Rice University website.
“We had an estimate of where we wanted to place the needle. And when we did, it worked, the first time, right off the bat. I don’t even know how to describe it, that moment.”
The scientists succeeded in getting the dead spider to grasp a tiny ball, and they utilized that experiment to calculate the highest grip force, which was 0.35 millinewtons.
They then performed a demonstration in which a dead spider was used to pick up fragile items and electronics, removing a jumper wire from an electric breadboard and moving a block of polyurethane foam afterward.
Additionally, they demonstrated that the spider could support the weight of another spider of a similar size.
When a spider dies, the hydraulic system ceases to function because it extends its legs by applying hydraulic pressure from its cephalothorax. The spider curls up when the flexor muscles in its legs develop into rigor Mortis because they can only move in one direction.
While manufacturing the majority of man-made robotics components is highly sophisticated, spiders are already quite complex and, sadly for arachnophobes, are readily available.
“The concept of necrobotics proposed in this work takes advantage of unique designs created by nature that can be complicated or even impossible to replicate artificially,” the researchers say in their paper.
Since spiders can be biodegraded, utilizing them as robot parts would reduce waste in the robotics industry.
“One of the applications we could see this being used for is micro-manipulation, and that could include things like micro-electronic devices,” says Preston in the video.
“We think that’s related to issues with dehydration of the joints. We think we can overcome that by applying polymeric coatings,” explains Preston.
When the wolf spiders were coated in beeswax, the researchers found that over the course of 10 days, their mass decreased 17 times less than the uncoated spider, indicating that the beeswax increased water retention and prolonged hydraulic system function.