I’ve been interested in robotics going back to my college days and have kept a pretty close eye on the amazing strides that have been made over the years. (Now that I think about it, make that decades.) As amazing as those strides have been – including, of course, the strides made by one of my favorite robots, Boston Dynamics’ robotic dog, which can climb stairs and open doors – I’m finding Rice University’s use of dead spiders to do some robotic lifting especially amazing. Dead spiders are being deployed as “necrobotic” grippers that can lift more than their own body weight.
As with so many scientific discoveries, this one came about through a casual observation unrelated to any scientific purpose.
Here’s how the invention of necrobotics happened.
Researchers at Rice University’s School of Engineering were setting up a lab at the department of mechanical engineering.
While they were moving things around, they came across a dead spider, and noticed that the spider had reverse engineered its demise. Rather than curling up and dying, spiders, it seems, die and curl up. Researchers being researchers, they wanted to know why. Turns out that unlike those of us with antagonistic muscle pairs of flexors and extensors, like biceps and triceps, or hamstrings and quadriceps, spiders just have flexor muscles. These let their legs curl in, and they use hydraulic pressure to extend out. That pressure goes away when the spider dies, so they literally curl up.
The lab was that of Daniel Preston.
[His] lab specializes in soft robotic systems that often use nontraditional materials, as opposed to hard plastics, metals and electronics. “We use all kinds of interesting new materials like hydrogels and elastomers that can be actuated by things like chemical reactions, pneumatics and light,” he said. “We even have some recent work on textiles and wearables.
“This area of soft robotics is a lot of fun because we get to use previously untapped types of actuation and materials,” Preston said. “The spider falls into this line of inquiry. It’s something that hasn’t been used before but has a lot of potential.” (Source: News – Rice University)
Anyway, Preston’s team went off and started figuring out what they could do with their observation of curled up spiders. Turns out, that once it’s dead and gone, a spider provides “’the perfect architecture for small scale, naturally derived grippers.” (Plus they’re biodegradable, so none of the waste issues associated with the components that are traditionally used.)
Setting up a spider gripper was fairly simple. [Researcher Faye] Yap tapped into the prosoma chamber with a needle, attaching it with a dab of superglue. The other end of the needle was connected to one of the lab’s test rigs or a handheld syringe, which delivered a minute amount of air to activate the legs almost instantly.
The lab ran one ex-spider through 1,000 open-close cycles to see how well its limbs held up, and found it to be fairly robust. “It starts to experience some wear and tear as we get close to 1,000 cycles,” Preston said. “We think that’s related to issues with dehydration of the joints. We think we can overcome that by applying polymeric coatings.”
Among the tasks they set for their necrobotic spider, they had the grippers manipulate a circuit board, move objects and even lift another spider.
Preston sees that future applications could include microelectronic assembly.
“Another application could be deploying it to capture smaller insects in nature, because it’s inherently camouflaged,” Yap added.
This ability to capture an insect that’s the bodyweight (or even larger than) the necrobotic spider could come in handy, given that researchers will need to have a supply chain of dead spiders for their work.