Batty Ability

Dusk falls on a dense forest in China’s Shandong province. As the sun dips below the horizon, hundreds of horseshoe bats swoop from the mouth of a cave. They dart across the dark sky, nabbing insect after insect. Before the sun rises the next morning, each bat will have eaten as many as 8,000 bugs—without bumping into a single tree or colliding with another bat. They accomplish this feat by using echolocation, a sixth sense that allows them to “see” using sound waves.

The bats navigate with high-pitched squeaks, many of which humans can’t hear. By listening to how their calls reflect, or bounce, off objects, they can map their surroundings. It’s an ability no human technology comes close to matching. But Rolf Mueller wants to change that. 

Mueller is a mechanical engineering professor at Virginia Tech University in Blacksburg, Virginia. He’s attempting to design high-tech navigation systems that mimic bats’ amazing abilities. These systems could, for example, enable drones to maneuver in dark, cramped spaces like disaster zones more easily.

Dusk falls on a dense forest in China’s Shandong province. The sun dips below the horizon, and hundreds of horseshoe bats swoop from the mouth of a cave. They dart across the dark sky. As they fly, they nab insect after insect. Before the next morning, each bat will have eaten as many as 8,000 bugs. And they’ll do it without bumping into a single tree or hitting another bat. They perform this feat by using echolocation. This sixth sense allows them to “see” using sound waves.

The bats find their way with high-pitched squeaks. Humans can’t hear many of these bat calls. The flying creatures listen to how their calls reflect, or bounce, off objects. That way, they can map their surroundings. No human technology comes close to matching this ability. But Rolf Mueller wants to change that. 

Mueller is a mechanical engineering professor at Virginia Tech University in Blacksburg, Virginia. He’s trying to design high-tech navigation systems that imitate bats’ amazing abilities. These systems could be used in drones, for example. They would help these devices to find their way through dark, cramped spaces like disaster zones more easily.

Bats emit chirps—some through their mouths and others through their noses—as many as 200 times per second. When the sound waves hit an object, like a tree or an insect, they reflect back to the bat’s ears. The echo gives the bat information about the object’s size and location, and whether it’s moving and how fast (see Seeing With Sound). 

A device called sonar, which is used in submarines, operates on the same principles as echolocation. But it requires large, cumbersome arrays of transmitters to produce sounds and microphones to detect their echoes. To Mueller, it seemed logical to turn to bats for inspiration to improve sonar technology. Nature, he says, has already designed echolocation—a more elegant and sophisticated version of sonar.

Bats let out chirps, as many as 200 times per second. Some come through their mouths and others through their noses. The sound waves hit an object, like a tree or an insect. Then they reflect back to the bat’s ears. The echo tells the bat the object’s size and location. It also tells if the object is moving and how fast (see Seeing With Sound).

A device called sonar is used in submarines. It works using the same ideas as echolocation. But it needs large transmitters to make sounds and microphones to pick up echoes. Mueller wanted to improve sonar. It made sense to turn to bats for help. Nature has already designed echolocation—an advanced version of sonar.

To learn more about how bats’ noses and ears aid in echolocation, Mueller needed to examine these features up close. He began tracking down and capturing bats in the wild. But then he discovered an easier way to compare the anatomy of bats from around the world: Go to the Smithsonian Institution’s National Museum of Natural History.  

Mueller set out to learn more about how bats’ noses and ears help in echolocation. He needed to examine them up close. So he began catching bats in the wild. He wanted to compare bats from around the world. Then he found an easier way: Go to the Smithsonian Institution’s National Museum of Natural History.

The museum, located in Washington, D.C., houses more than 125,000 preserved bat specimens. Mueller made molds of some of the bats’ noses and ears. Then he switched to studying them using a 3-D scanner. This device creates a digital copy of an object’s shape (see 3-D Scan). So far, Mueller has catalogued the ears and noses of more than 100 bat species.

The museum is in Washington, D.C. It holds more than 125,000 preserved bats. Mueller made molds of some of the bats’ noses and ears. Then he studied them using a 3-D scanner. This device makes a digital copy of an object’s shape (see 3-D Scan). So far, Mueller has recorded the ear and nose shapes of more than 100 bat species.

Using that information, Mueller has created a bat-inspired sonar system (see Copying Bats). The device has a “nose” with rubber-like silicone flaps and a speaker that emits sound. The device also has “ears”—two microphones surrounded by silicone. Tiny motors move the flexible features to change their shape, just as bats do.  

Mueller has already put that information to use. He’s created a bat-inspired sonar system (see Copying Bats). The device has a “nose” with rubber-like silicone flaps and a speaker that produces sound. It also has “ears.” They’re two microphones surrounded by silicone. Tiny motors move the flexible features to change their shape, like bats do.

Mueller is testing the device in his lab in Blacksburg. He’s also strapping it to a zip line and sending it zooming through the forest near Virginia Tech’s laboratory in Shandong to see how well the system detects objects in its path. Once the device is perfected, Mueller plans to attach it to a small flying drone. It will whiz through the dark jungle alongside real bats. Someday, the sonar-guided drones could perform ground surveys, help farmers monitor their crops, and even deliver packages to homes. 

“Having the drone is one thing—now what can you do with it?” says Mueller. “That is something that’s going to keep us busy for years to come.” 

Mueller is testing the device in his lab in Blacksburg. He’s also strapping it to a zip line and sending it zooming through the forest near Virginia Tech’s laboratory in Shandong. This will show how well the system detects objects in its path. Once the device is perfected, Mueller plans to attach it to a small flying drone. It will whiz through the dark jungle alongside real bats. Someday, the sonar-guided drones could perform ground surveys and help farmers watch their crops. They could even deliver packages. 

“Having the drone is one thing—now what can you do with it?” says Mueller. “That’s going to keep us busy for years to come.”