As humans, one of our greatest traits is our desire to learn from the world around us. We take that knowledge and use it to make our lives better. Countless lessons can be learned from nature, how creatures presumably less advanced than humans can survive in the world. Since the dawn of flight, engineers and scientists have studied how naturally flying creatures such as birds and insects fly. The physiology and neurological connections of these creatures have greatly influenced the progression of aerial vehicles. In recent times, scientists have begun studying the animal world for inspiration in designing new drones, the next frontier of aerial vehicles.

Researchers have applied characteristics from hummingbirds, dragonflies, bats, and even flying squirrels to develop drones. This is called biomimicry, the application of biology from nature to solve human problems. Some of the biomimetics found in drone technology include the way a drone can hover like a hummingbird, fly in any direction like a dragonfly, or conserve energy by gliding like a flying squirrel. Even box turtles are inspiring drone designers as one research team is designing the parcel payload of a delivery drone on the turtle’s shell. In December of 2020, a graduate student from the University of Washington published her findings on not just applying biomimicry to a drone, but an actual living body part of an animal to enhance how a drone can navigate.

Mechanical engineering Ph.D. student Melanie Anderson joined Professor Thomas Daniel’s biology lab, aptly called the Daniel Lab, to develop a drone that uses the navigational processing of a moth. The Daniel Lab has conducted many research projects on how the molecular, cellular, and neurological biology of hawkmoths enable their unique flight abilities. Hawkmoths are different from other moths because of their ability for sustained flight, often compared to that of a hummingbird. Though moths do use vision to assist in their flight, many can fly through complex environments because of their antenna. The hawkmoth’s antenna is less feathery than other moth species, but are covered in sensors that allow them to smell out a flight plan.

It was the structure of the hawkmoth’s antenna that was of interest to Melanie and how they could be used to control a drone’s navigation. A hawkmoth’s antenna is so finely tuned to smelling out food sources, that it can find these food sources in the dark. “Cells in a moth antenna amplify chemical signals,” said Professor Daniel. “The moths do it really efficiently — one scent molecule can trigger lots of cellular responses, and that’s the trick. This process is super efficient, specific, and fast.” But as Melanie pointed out, being able to mechanically engineer a structure to mimic a moth’s antenna would never be as good as the real thing.

Finding a way to biometrically apply a moth antenna to a drone would not work, so Melanie and Profesor Daniel found a way to attach a living moth antenna to a drone they named the Smellicopter. “Nature really blows our human-made odor sensors out of the water,” Melanie said. “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.” The resulting product, a drone that can autonomously smell its way along a path, towards a target, without colliding with obstacles.

Before removing the live antenna, the moths were placed in a freezer to anesthetize them. Once removed, the antenna’s ability to chemically and biologically respond to stimulants lasts up to four hours, a time that could be extended with refrigeration. Melanie then adhered the antenna to a fine wire. The wire is bent into an arch and connected to an electrical circuit on a drone small enough to fit in the palm of your hand. The team also added a dual plastic fin on the back of the drone to make sure it would fly upwind at all times, allowing the antenna to maintain the chemical connection to the target scent.

To test the drone, Melanie placed it in a wind tunnel with vertical obstacles. At the end of the tunnel was a dish filled with a scent the antenna would naturally respond to. As the fan blew gusts of wind down the tunnel the antenna on the drone picked up the chemical signature of the fragrance. The drone was programmed to mimic the swaying flight characteristics of a moth that in nature would allow its antenna to pick up a scent before progressing forward. Sensors on the drone registered any obstacles, causing the drone to once again sway to pick up the scent signal. Melanie also tested a man made odor sensor in the experiment. The electrical sensors on both drones showed that the one with the live antenna attached reacted with greater speed and accuracy.

Because the Smellicopter navigates by smelling its environment, it does not need to use GPS or rely on any internet connection to work. This is of particular use if the drone were to be used in real world situations. Melanie foresees the Smellicopter as being useful in detecting gas leaks or unexploded IEDs. When searching for such substances, a small drone that can operate without an internet connection is often necessary. “Being able to locate the source of an odor is a huge field,” Melanie said, “so by taking basically the best- by using the moth antenna- which is super fast, low powered, highly sensitive, even if that’s not the longterm goal, it’s something that manmade sensors actually can’t do.” Melanie’s Smellicopter is just another example of how humans will continue to use the wonders of the natural world for technological advancement.

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