When mechanical engineering student Faye Yap saw a dead spider curled up in a hallway, she started thinking about its potential use as a robotic component.
Turning dead spiders into mechanical grips might be some people’s idea of a nightmare scenario, but it can have tangible benefits. Spider legs can grip large, thin, and irregularly shaped objects firmly and gently without breaking them.
So did Daniel Preston, a mechanical engineer, in collaboration with colleagues at Yap and Rice University discovered method of opening the legs of a dead wolf spider and attaching them to objects.
They called this new robotic technique “necrobotics”.
Strangely enough, spiders do not have muscles to extend their legs, but instead move their legs by hydraulic pressure – they have a prosoma chamber or cephalothoraxwhich contracts, sending internal body fluid to the legs and forcing them to extend.
So the team inserted a needle into the spider’s prosoma chamber and created a seal around the tip of the needle with a glob of superglue. A small squeeze of air from the syringe was enough to activate the spider’s legs, achieving full range of motion in less than a second.
“We took the spider, put the needle in it without knowing what was going to happen,” says Yap. video on the Rice University website.
“We had figured out where we wanted to put the needle. And when we did, it worked the first time, right away. I don’t even know how to describe that moment.”
The team managed to catch the dead spider in a small ball and used this experiment to determine a peak grip force of 0.35 millinewtons.
They then demonstrated the use of a dead spider to pick up delicate objects and electronics, including this necrobotic grabber removing a jumper wire attached to an electrical board and then moving a block of polyurethane foam.
They also showed that the spider can carry the weight of another spider of roughly the same size.
(Preston Innovation Lab/Rice University)
Because spiders extend their legs by applying hydraulic pressure from their legs cephalothorax, when they die, the hydraulic system no longer works. The flexor muscles of the spider legs are inserted hard deathbut because the muscles work in only one direction, the spider twists upwards.
While most artificial robots are quite complex to manufacture, spiders are already sophisticated and (unfortunately for arachnophobes) in plentiful supply.
“The concept of necrobotics proposed in this work uses unique designs created by nature that are difficult or even impossible to reproduce artificially,” the researchers said. paper.
Spiders are also biodegradable, so using them as robot parts would reduce the amount of waste in robotics.
“One of the applications we can see used for this is micro-manipulation, and that could include things like micro-electronic devices.” he says Preston in the video.
One drawback of the dead spider catcher is that after two days or 1000 open-close cycles it starts to wear out a bit.
“We think it’s related to joint dehydration issues. We think we can overcome that by applying polymer coatings.” explain Preston.
The researchers experimented with coating wolf spiders in beeswax and found that over 10 days, the spider’s mass was 17 times less than that of an uncoated spider, meaning it could hold more water and its hydraulic system could work longer.
This study was published Advanced Science.
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