The ability to track down certain smells can literally be the difference between life and death in certain situations, such as trying to source the breath of victims trapped under rubble or locate an unexploded bomb. Human noses unfortunately are somewhat lackluster in this department, but the antennae of moths are fine-tuned smell detectors. Combine that with an autonomous drone that can avoid obstacles and what do you get? Meet the Smellicopter.
The Smellicopter was created as part of a study published in the journal IOP Bioinspiration & Biomimetics. Led by a team from the University of Washington, the autonomous drone was crafted to use live antennae from a moth to find smells in places that are hard for humans to access due to logistical or safety reasons.
The ability to sniff out chemicals in the air has many applications but when human-made or human-grown materials failed to deliver the sensitivity needed for this kind of technology, the team turned to nature for an alternative. Moth antennae can sense fleeting plumes of chemicals as they flap about in the environment. They are highly sensitive, amplifying the chemical signals they detect, which trigger cellular responses in the moth.
To make the most of these natural odor detectors, the researchers placed live Manduca sexta hawkmoth specimens into a fridge as the cold acts like an anesthetic. They then removed the moths’ antennae and attached it to the Smellicopter using tiny wires that could translate the signal strength of odors picked up by the antennae. These antennae remained biologically and chemically active for four hours after being removed, and stayed active for even longer when stored in a fridge.
Next, they needed to enable the drone to overcome obstacles in its path, so they created a “cast and surge” protocol that was inspired by the way moths seek out scents. The drone begins scanning an area by moving to the left, then if it doesn’t pick up on any chemically significant cues, it travels the same distance to the right. When it detects a scent, its flight path will move in the direction of the chemical cue with infrared sensors to pick up on physical obstacles. When such an obstacle comes within 20 centimeters (8 inches) of the drone, it will switch back to its left-to-right casting flight path to get around it.
"So, if Smellicopter was casting left and now there's an obstacle on the left, it'll switch to casting right," said lead author Melanie Anderson, a UW doctoral student in mechanical engineering, in a statement. "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.
"Nature really blows our human-made odor sensors out of the water. 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."