Compact flying machines are nothing new, and researchers have already created many robots that mimic insects. But now, researchers at North Carolina State University have created a small robotic bat using “smart” materials.

Micro-aerial vehicles can maneuver in small spaces and could be ideal for surveillance tasks. Robert Wood at Harvard has worked for nearly a decade on a robotic fly, and researchers in Germany and England are building dragonfly robots. But designing and building such small flying machines is tricky. They tend to be aerodynamically inefficient, and it’s hard to mimic movements like the flapping of wings mechanically.

To create their “robo-bat,” the NC State researchers analyzed a bat’s muscular and skeletal system, and then used rapid prototyping technologies and smart materials to recreate it. From the press release, here’s Stefan Seelecke, a professor of mechanical and aerospace engineering at NC State, who helped build the bat:

“We are using a shape-memory metal alloy that is super-elastic for the joints. The material provides a full range of motion, but will always return to its original position–a function performed by many tiny bones, cartilage and tendons in real bats.”

Seelecke explains that the research team is also using smart materials for the muscular system. “We’re using an alloy that responds to the heat from an electric current. That heat actuates micro-scale wires the size of a human hair, making them contract like ‘metal muscles.’ During the contraction, the powerful muscle wires also change their electric resistance, which can be easily measured, thus providing simultaneous action and sensory input. This dual functionality will help cut down on the robo-bat’s weight, and allow the robot to respond quickly to changing conditions–such as a gust of wind–as perfectly as a real bat.”

The bat weighs less than six grams and can fit in the palm of your hand.