Over the years, drones have proven their mettle in a variety of situations. They have been used in law-enforcement, tackling man-animal conflicts, among a host of other purposes. In the very near future, they are also being designed to deliver food to our doorsteps.
Now, researchers at the University of Washington (UW) are interested in developing drones that can navigate certain situations—such as unsafe buildings affected by natural disasters or regions that have unexploded devices—by sniffing out chemicals in the air to locate disaster survivors, gas leaks, explosives and much more. However, most sensors created by people are not sensitive or fast enough to be able to find and process specific smells while flying through the odor plumes these sources create.
A team led by UW researchers has developed the ‘Smellicopter’—a tiny autonomous drone that uses an actual live antenna from a moth to navigate toward smells. According to an official news release from the UW website, ‘Smellicopter’ can also detect and avoid obstacles as it flies.
The team used antennae from the Manduca sexta hawkmoth. Researchers placed moths in the fridge to anesthetize them before removing an antenna, the release explains. Once separated from the live moth, the antenna stays biologically and chemically active for up to four hours. That time span could be extended, the researchers explained, by storing antennae in the fridge. Moths use the antennae to sense chemicals in the environment around them to find sources of food or even mates.
“By using an actual moth antenna with Smellicopter, we’re able to get the best of both worlds: the sensitivity of a biological organism on a robotic platform where we can control its motion,” said Melanie Anderson, a UW doctoral student in mechanical engineering and lead author of the study, which described the results of this research in the IOP Bioinspiration & Biomimetics journal recently.
The researchers added small wires into either end of the antenna to connect it to an electrical circuit and measure the average signal from all of the cells in the antenna. “The team then compared it to a typical human-made sensor by placing both at one end of a wind tunnel and wafting smells that both sensors would respond to: a floral scent and ethanol, a type of alcohol,” the release explains. The antenna reacted more quickly.
Technology-wise, the team added the antenna sensor to an open-source hand-held commercially available quadcopter drone platform that allows users to add customized features. They also added two plastic fins on the back of the drone to create drag to help it be constantly oriented upwind.
Interestingly, the drone does not need any help from the researchers to detect smells or odor. They created a “cast and surge” protocol that helps the drone mimic how moths search for smells. “Smellicopter begins its search by moving to the left for a specific distance. If nothing passes a specific smell threshold, Smellicopter then moves to the right for the same distance. Once it detects an odor, it changes its flying pattern to surge toward it,” the release explains. It also avoids any physical obstacles with the help of four infrared sensors. There’s no GPS. Instead, the drone relies on a camera to survey its surroundings—just like the eyes of an insect. This tiny innovation uses the principles of biomimicry quite beautifully.