Deceased spider inspires new field of "necrobotics"

Researchers at Rice University in Texas have repurposed a body of a dead spider as a mechanical gripper, unsettling the internet.

As Daniel Preston, an assistant professor of mechanical engineering at Rice University, was setting up his new lab, a lifeless spider lying in the corner caught his and graduate student Faye Yap's attention.

As spiders die, their legs retract – the two wondered why that was the case. A quick search showed that spiders use hydraulics to move their limbs – unlike humans and other mammals, who have antagonistic muscle pairs, like biceps and triceps.

"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," Yap said in a university's press release.

Preston's lab focuses on using non-traditional materials in robotics, and a humble spider turned out to have a "perfect architecture" for a biological gripper. The process of hacking the spider's hydraulic process turned out to be relatively simple – a gush of air through a needle attached to the spider's prosoma, or internal valves, activated its legs.

The study, published by Advanced Science, experimented with the carcasses of wolf spiders to carry out tasks such as lifting other spiders or manipulating a circuit board. The scientists say that using biotic material as mechanical components marks the first step in an area they dubbed "necrobotics."

Image by Preston Innovation Laboratory/Rice University.

The research – but mostly accompanying visuals – have led to some public unease. For the scientists behind the study, however, this is no "stuff of nightmares" but rather a new area of technology with a potentially varied practical application.

"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," Preston was quoted as saying in the university's press release.

As it comes with natural camouflage, the spider gripper could also be deployed in nature to capture smaller insects – especially when the task requires delicate handling.

The study showed that it could lift an object 130% of its own weight or sometimes more. Curiously, the smaller the spider, the heavier loads it can carry compared to its size.

The scientists say that the spider's legs are "fairly robust". They can go through up to 1,000 actuation cycles before starting showing some wear and tear – a problem they believe they can overcome by applying polymeric coatings.

As necrobotic grippers naturally biodegrade at the end of their lifespan, it could also lead to more environmentally friendly research – euthanized spiders notwithstanding.