Mechanical engineers at Rice University have found a way to repurpose dead spiders with a puff of air making them into grippers.
The project began shortly after Daniel Preston established his lab in Rice’s Department of Mechanical Engineering in 2019, specialising in soft robotic systems that use non-traditional materials.
Experimenting with dead spiders may sound to some people like the stuff of nightmares, but Preston said it wasn’t planned and stemmed from finding a spider curled up in the hallway.
Preston and graduate student Faye Yap set out to discover why spiders curl up when they die and found that spiders do not have antagonistic muscle pairs.
“So in a human, we have our biceps and our triceps, they work to both flex and then extend the elbow joint. But when you think about spiders, they have flexor muscles that will bring their joints and appendages in towards the body. But they don’t have extensors, and instead, they do that with hydraulic pressure that they generate inside of the main cavity or chamber of their body. And so because of that, when they die, that’s why you see spiders curled up,” explained Preston. “That means that we can use hydraulic pressure when we use the spider as the material for our gripper to take advantage of that and extend all of its legs or joints,” Preston added.
Keep reading about the spiders below, or take a minute to watch this piece Central Oregon Daily News did over the summer about the robber fly!
Yap and Preston harnessed a spider’s physiology in a first step toward a novel area of research they call ‘necrobotics’. The term ‘necrobotic’ because the objects being used are dead; dead spiders in this case but according to them it can be any kind of biotic material.
“You can imagine this is a similar material class to things like leather or bone if you imagine some of our early ancestors having developed tools from bones. This is an extension of that same concept this is ‘necrobotics’,” Preston said.
To set up a gripper the prosoma chamber of the spider is tapped with a needle, attaching it with a dab of superglue. The other end of the needle is then connected to a handheld syringe which delivers air to activate the legs.
The lab used wolf spiders in the research, which included manipulating a circuit board, moving objects and lifting objects. They found that the wolf spider could lift more than 130% its own body weight.
According to the research reports one ‘necrobotic’ spider was put through 1,000 open-close cycles to see how well its limbs held up, and found it to be fairly robust.
“One of the applications we could see this being used for is micromanipulation, and that could include things like microelectronic devices. We’re excited about it because it also offers the potential to reduce waste streams. So these grippers, as you might guess, made from these biotic materials, are compostable or biodegradable,” said Preston.
The prospect of using ‘necrobotic’ spiders has many advantages, not just for the environment. The size of a spider versus the size of human fingers when operating certain applications and the added bonus that the cost of making a gripper would be reduced as they are created from a natural resource.