Why bother designing your own robots when you can just reuse what nature created?
This was the thought process behind a research project by Rice University engineers who successfully turned dead spiders into robotic grasping claws. The scientists have dubbed their new research area ‘necrobotics’ and say it could create cheap, effective and biodegradable alternatives to current robotic systems.
So why spiders? Well, while humans move their limbs using antagonistic muscle pairs like biceps and triceps, spider legs contain only a single flexor muscle that pulls the leg inward. This is opposed by a hydraulic system: a chamber in the center of the spider’s body (known as the prosoma) pushes out fluid to open the leg, with separate valves allowing the animal to control each limb independently. Incidentally, this is why spiders always curl up when they die; There is no pressure in the system that counteracts the flexor muscles of the legs.
Armed with this knowledge, the Rice University team discovered that they could artificially operate this hydraulic system simply by sticking a needle into the prosoma of a dead spider and forcing air in and out to twist the spider’s legs like an arcade claw machine to open and close.
You can watch a video of their work in action below:
“It’s like, once dead, the spider is the perfect architecture for small, naturally derived claws,” said Daniel Preston of Rice’s George R. Brown School of Engineering in a press release. The spiders can lift more than 130 percent of their body weight and go through 1,000 open-close cycles before the joints degrade.
The Rice University team, led by graduate student Faye Yap, did just that published a paper describing their work in the diary Advanced Science. In it, they note that humankind has a long history of reusing the remains of dead organisms for new purposes — from animal skins worn as clothing to bones sharpened into arrowheads and tools. In this context, turning a dead spider into a robotic gripper is not as unusual as it might first appear.
The scientists also note that roboticists often take inspiration from and copy nature for their designs Adhesive surface of gecko feet or the waves of a fish tail, for example. But, they argued, why copy when you can steal? Especially when Mother Nature has already done the hard work of developing effective mechanisms over millions of years of evolution.
As they write in the paper: “The concept of necrobotics proposed in this work takes advantage of unique nature-created designs that are complicated or even impossible to replicate artificially.”
The group ordered their test subjects from an organic delivery company, reports gizmodo, which caused some problems for arachnophobic colleagues. As Rice’s Preston told the publication, “One of the employees who works in our front office really doesn’t like spiders. So we had to call the front office when another shipment arrived for us to use on the project and just give them an advance warning.”
For now, the work is essentially a proof of concept, but Preston said it could have many future applications. “There’s a lot of pick-and-place tasks that we could study, repetitive tasks like sorting or moving objects at these small scales, and maybe even things like assembling microelectronics,” he said in a press statement.
Another use could be collecting animal specimens in nature, Yap said, since a spider claw is “inherently camouflaged.”