University of Washington researchers have created a drone — a Smellicopter — a drone that is able to accurately detect odors by using a live moth antenna. This moth antenna has two tiny wires that come out of it and are connected, at each end, to a circuit, which enables the drone to detect (smell) accurately.
By using the antenna to fly toward odors, the “sniffing drone” can fly autonomously while also simultaneously avoiding obstacles. The primary reason researchers explored using biological sensors is due to the fact that nature is much better than those we humans can create.
The lead author and doctoral student in mechanical engineering at University of Washington, Melanie Anderson, explained:
“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.”*
Moths were chosen for this experiment because they use their antennae to detect chemicals in the air surrounding them and their antennae only needs one molecule of a chemical to trigger a range of their responses. This is obviously something human-made sensors are unable to do.
The antennae used in the research are placed in a refrigerator to anesthetize it before the antennae are removed. Once disconnected, the antennae can stay alive for about four hours, although it can be extended when it is stored in a refrigerator to be used later.
Once the antennae are attached with a wire at each end to a circuit, researchers are able to measure the average signal from it, and even add certain smells to the air, for the purpose of seeing how it will react for later autonomous flights.
The moth antennae have been tested against human-made sensors at the end of a wind tunnel, and as the smells were slowly added, the biological sensors reacted faster, and required less time to recover between the smells.
The antenna was added to an open-source drone, and two fins were also added to the drone to help keep it upwind at all times. After the completion of the testing phase, the team created a cast and surge protocol that enables the drone to function like a moth.
The Smellicopter flies in a certain direction to a predetermined distance, and if it doesn’t detect a smell, it goes in another direction until a smell is detected, unless the distance is unreasonable.
The Smellicopter is equipped with four infrared obstacle avoidance sensors that update 10 times a second to keep it safe while in the air.
Anderson explained how this works:
“So if Smellicopter was casting left and now there’s an obstacle on the left, it’ll switch to casting right. And if Smellicopter smells an odor but there’s an obstacle in front of it, it’s going to continue casting left or right until it’s able to surge forward when there’s not an obstacle in its path.”*
When the moth drone was tested, it was equipped with a camera rather than GPS, and it was programmed to fly toward smells that moths find interesting, such as floral scents. But researchers hope that future work could have the moth antenna sense other smells, such as carbon dioxide, which is inhaled by someone trapped under rubble, or the chemical signature of an unexploded device.
Future
One of the great advantages of drones, such as Smellicopters, is that they are small robots or aerial robots (drones), which can go in so many places on land or in the air that people can’t go.
In the future, Smellicopters can potentially save many lives as they can be programmed to detect and fly toward dangerous odors, such as carbon dioxide, a deadly odor that too often contributes to the death of numerous victims who may be unaware of its danger. It may include areas that might be too dangerous, such as unstable structures after a natural disaster, a region with unexploded devices, hazardous odors, or in various other ways.
