Biomimicry, or using the motion of animals as inspiration for design, has long been a staple of robotics and engineers have studied animals to solve complex structural problems. Recently, researchers from the University of California, Berkeley, created a small robot — inspired by an African primate called galago — that can jump over three times its full height.

And on Wednesday, engineers from the University of Illinois at Urbana-Champaign and California Institute of Technology (Caltech) announced they had created a bat-inspired flying robot, which uses soft, flexible wings and is significantly more energy efficient than current aerial robots. Their research appeared in the journal Science Robotics in a paper titled “A biomimetic robotic platform to study flight specializations of bats.”

Called Bat Bot (B2), the flying bots are modeled after the fastest flying mammals that have among the most complex and sophisticated flight mechanisms among all animal species. Over 40 types of joints interlock the bones and muscles of bats when they are in flight, allowing them to change the shape of their wings that can move in multiple independent directions.

“Our work demonstrates one of the most advanced designs to date of a self-contained flapping-winged aerial robot with bat morphology that is able to perform autonomous flight. It [B2] weighs only 93 grams, with dynamic wing articulations and wing conformations similar to those of biological bats,” Alireza Ramezani, a postdoctoral researcher at University of Illinois, said in a statement.

A dynamic skeleton array and a silicone-membrane skin allow B2 to change its structure while in mid-flight without losing its aerodynamic surface.

“The B2 possesses a number of practical advantages over other aerial robots, such as quadrotors. Bats do have more 40 active and passive joints; we reduced those numbers to 9 (5 active and 4 passive) joints in the B2 robot. The compliant wings of a bat-like flapping robot flapping at lower frequencies (7-10 Hz vs. 100-300 Hz of quadrotors) are inherently safe: because their wings comprise primarily flexible materials and are able to collide with one another, or with obstacles in their environment, with little or no damage,” Soon-Jo Chung of Caltech explained in the statement.

In a separate development, also related to biomimicry, engineers from the Massachusetts Institute of Technology (MIT) announced Wednesday they have created transparent hydrogel robots that move when water is pumped in and out of them, and depending on their design, can perform a number of tasks, including catching and releasing live fish.

Hydrogel is “a tough, rubbery, nearly transparent material that’s composed mostly of water,” and the MIT robots are made almost entirely using that material. They are connected with rubbery tubes, through which the researchers pumped water in or out of the robots to inflate or collapse them. Given the material, they are almost invisible when underwater.

To create fast and forceful motions in the robots, Xuanhe Zhao, an associate professor at MIT, and graduate student Hyunwoo Yuk studied animals, specifically glass eels, whose larvae hatch in the ocean before migrating to their natural freshwater river habitats.

They found the structure they designed could withstand up to 1,000 cycles of repeated use without rupturing or tearing. And using a mechanism to quickly inundate the structures with water gave the robots their speed and force, which is lacking in other similar robots that let water naturally seep inside. To demonstrate the capabilities of the robots, Zhao and Yuk showed one catching and releasing a live goldfish, and another kicking a ball underwater.

In a statement, Zhao said given the nature of hydrogel, their designs could find applications in the field of surgery.

“Hydrogels are soft, wet, biocompatible, and can form more friendly interfaces with human organs. We are actively collaborating with medical groups to translate this system into soft manipulators such as hydrogel ‘hands,’ which could potentially apply more gentle manipulations to tissues and organs in surgical operations,” he said.

A research paper about the hydrogel robots made by the MIT team appeared in the journal Nature Communications under the title “Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water.”