Melanie Anderson pulls aside a small curtain in a dark closet. A dim red bulb is the only light.
鈥淭his might take a while because I want to grab male moths,鈥� she says, reaching into the cage behind the curtain.
She pulls out a mottled brown, sometimes called the Carolina sphinx moth. It鈥檚 big 鈥� larger than her palm.
鈥淭hat looks like a female. It has slightly smaller antennae,鈥� she says. 鈥淪o I鈥檓 going to put it back.鈥�
For this engineer, the antennae are the key.
Anderson reaches once, then twice more into the fluttering mass of insects in the cage. She finally snags a male.
This moth鈥檚 antennae have a cyborg destiny aboard a called the 鈥�.鈥�
鈥淚 tell people 鈥榤oth antenna鈥� and they鈥檙e like, 鈥榃hat does 鈥楳OTH鈥� stand for?鈥� And I鈥檓 like, 鈥楴o, no, no. The insect,鈥� Anderson explains. 鈥淲e actually use a live biologic component of the moth 鈥� the antenna 鈥� and we put it on an electrical circuit to read signals from it.鈥�
But Smellicopter is more than just cutting-edge bio-hybrid technology, it鈥檚 an innovation that could make us safer in the face of accidents and disasters.
Super smellers
A moth鈥檚 antennae are an evolutionary masterpiece of smell. They can pick up the faintest of scents.
鈥淏iology can detect chemicals at a level that far exceeds anything that鈥檚 synthetic 鈥� not by a factor of a 1000 or 10,000 or 100,000 or even a million factors. Even greater than that,鈥� said. 鈥淪o, we use the extreme sensitivity of odor detection in living systems and asked, 鈥楬ow could we integrate it into synthetic systems?鈥欌��
Daniel, who鈥檚 head of a looking at nature-inspired flight systems, asked Anderson this question, and she鈥檚 gotten her Ph.D. answering it.
Anderson and her research partner Joseph Sullivan have created a drone that taps into the extraordinary sensory power of a moth鈥檚 antenna.
鈥淵ou can have it in a chemical plant to be able to survey that area and find the source of an odor leak or a gas leak very quickly before it gets out of hand,鈥� Anderson said. 鈥淚t can be used to replace search dogs or search and rescue workers in dangerous situations. So it can really save lives.鈥�
It works by bringing biology, robotics, coding, aerodynamics and a host of other disciplines together to create one device.
After cutting the antenna off an anesthetized moth, Anderson uses tweezers to thread the hollow structure onto a hair-like wire of a circuit.
鈥淪he can manipulate that antenna and get that tiny silver wire inside of it. And she doesn鈥檛 need a table or anything 鈥� I cannot,鈥� Sullivan says, watching Anderson鈥檚 steady hands.
鈥淕ive it a couple more months of and you鈥檒l have the same dexterity,鈥� Anderson quips back.
She bends the antenna over to tread the other end onto the opposite wire. The loop of the antenna completes the circuit.
When the moth antenna encounters certain odors, it reacts, creating faint signals running between the two wires.
鈥淲e鈥檙e measuring electrical activity in the antenna, which is very, very faint,鈥� Sullivan says.
Some moths eat flower nectar, so their antennae are highly tuned to those smells.
鈥淓specially if I just showered, then sometimes it鈥檒l react to my shampoo or conditioner,鈥� she said.
The reaction can be seen on a line graph on her computer. In the ambient air, the line is fairly steady. But when Anderson puffs some floral scent across the antenna, it spikes. These spikes are what signal to the drone that the source of the odor is near.
鈥淓lectroantennogram鈥� odor sensors like this 鈥� but mounting them on a drone for use in disaster areas is new.
Inspired by Nature
The idea for Smellicopter came out of the U.S.. The group was comprised of scientists and engineers from several universities.
鈥淲e鈥檙e not very good at making odor sensors that will interface with a flying machine,鈥� said, a biologist who studies moths at in Ohio. 鈥淚f you think about it, flight is a kind of locomotion where everything is happening fast 鈥� If you can鈥檛 make quick adaptations, you鈥檙e gonna smack into something.鈥�
Willis is a member of the Center for Excellence but wasn鈥檛 directly involved in the creation of Smellicopter.
He said artificial odor sensors currently can鈥檛 respond quickly enough to meet the demands of flight. But a moth鈥檚 antenna is ideal because it can react in quick succession to odors in the environment with just under 100 milliseconds between responses.
鈥淪mellicopter is actually a great example of a beginning step while we鈥檙e busy trying to come up with a synthetic odor detector that will clear itself as quickly as a biological odor detector. We can just take the biological odor detector and slam it onto the robot,鈥� Willis said.
Smellicopter鈥檚 connection to the natural world goes even further than its living antenna. Anderson鈥檚 drone also looks to moths to inspire how the drone flies.
鈥淭he moths, when they smell odor鈥� they will surge upwind. And then when they lose the odor, like if the wind shifts or they get a little off course, then they cast back and forth crosswind until they find the odor again. And then they surge upwind again,鈥� she said.
In a small wind tunnel on campus, the cast and surge strategy of Smellicopter is put to the test. Anderson places a drop of the floral scent at the head of the tunnel and launches the small drone.
Smellicopter flies back and forth searching for the trail. It locks in and surges toward the scent.
鈥淭hat time it went straight to the source. It had a lot of hits right at that last surge,鈥� Anderson tells Sullivan.
鈥淵eah, I see that. Peak. Peak. Peak. Peak.鈥�
Smellicopter鈥檚 next evolution
If gas leaks, buried disaster victims and explosive devices all smelled like flowers, Smellicopter would be in business.
But they don鈥檛. And that鈥檚 the next big step in Smellicopter鈥檚 evolution.
鈥淲e are working towards so that they can sense different chemicals 鈥� Amplify the antenna鈥檚 sensitivity to things like bomb scents and then kind of remove the sensitivity to things that we don鈥檛 want 鈥� like the floral scent and the moth pheromone,鈥� Anderson said.
This work is underway now, as part of at UW. She鈥檚 also working on a cell phone-mounted electroantennogram that could be used as a handheld sensor.
Smellicopter hovers at the intersection of emerging technologies.
鈥淲e have device technologies, which is robotics, and neural recording technologies. We have. That鈥檚 crazy, contemporary technology,鈥� said Tom Daniel.
And it also offers a glimpse of what could be possible if you add artificial intelligence into the mix 鈥� the possibility of listening in on not just one signal coming from the moth鈥檚 antenna, but all of them at once.
鈥淭here are many cells in the antenna circuit coming into the animal, each one signaling different chemicals. Could we use machine learning to discern between 鈥業s that Tom?鈥� or 鈥業s that you?鈥� I know my dog can smell the difference between us,鈥� Daniel said.
鈥淪o can we combine gene editing, device technology and AI to make a sommelier?鈥�
And if we could make an artificial sensor that sophisticated, there鈥檚 no limit to where our new noses could take us next.
Copyright 2022
