This mantis shrimp-inspired robotic arm can crack an egg
We usually think of robots as being made out of hard, rigid materials, but soft robotics seeks to build robotic devices out of more flexible materials that mimic the properties of those found in living animals. Case in point: Korean engineers have built soft robots capable of rapid and powerful joint movements by employing the same mechanism that gives the mantis shrimp such a powerful punch, according to a new paper published in the journal Science Robotics.
As we’ve reported previously, mantis shrimp come in many different varieties; there are some 450 known species. But they can generally be grouped into two types: those that stab their prey with spear-like appendages (“spearers”) and those that smash their prey (“smashers”) with large, rounded, and hammer-like claws (“raptorial appendages”). Those strikes are so fast (as much as 23 meters per second, or 51 mph) and powerful, they often produce cavitation bubbles in the water, creating a shock wave that can serve as a follow-up strike, stunning and sometimes killing the prey. Sometimes a strike can even produce sonoluminescence, whereby the cavitation bubbles produce a brief flash of light as they collapse.
According to a 2018 study, the secret to that powerful punch seems to arise not from bulky muscles but from the spring-loaded anatomical structure of the shrimp’s arms, akin to a bow and arrow or a mousetrap. The shrimp’s muscles pull on a saddle-shaped structure in the arm, causing it to bend and store potential energy, which is released with the swinging of the club-like claw. It’s essentially a latch-like mechanism (technically, Latch-mediated spring actuation, or LaMSA), with small structures in the muscle tendons called sclerites serving as the latch.
