Now an electronic nose that can beat a mouse at its own game

Imagine a robot that can detect scents in air and track down ir sources as efficiently as a dog or a mouse. If realised, it could detect small wildfires in dense forests, find people buried in debris after an earthquake, or even hunt for truffles! research team at Western Sydney University has created a compact electronic se capable of identifying odours within milliseconds.

In study published in Science vances, goal was to explore this artificial sense of smell and test how fast we can extract valuable information about environment from air. We show that “speed of smell” matches and sometimes even exceeds those of mammals.

Complex and informative odour landscapes Animals perceive smells incredibly quickly, and this ability has evolved over millions of years to optimise ir chances of survival. But why is such speed necessary? answer lies in complex nature of how odours move through air. Unlike what you might think, odours don’t just grow steily weaker as you move away from ir source to where y are detected.

Inste, air movements create a highly chaotic environment where odours travel in irregular plumes that can be extremely brief and d out over time. se plumes are shaped by a mix of small- and large-scale turbulent air dynamics, including wind shearing and molecular diffusion, as well as by environmental boundary conditions.

Understanding se odour plumes is crucial for animals. Each brief encounter with an odour can carry valuable information.

For instance, by analysing timing and frequency of se odour bursts, an animal can estimate how far it is from source. If animal tices that two different odours always occur toger, it could mean ir sources are in close proximity to each or. Variations in concentration of se bursts can also hint at size and spre of odour plume.

se subtle clues help animals make quicker decisions about where to find food, avoid predators, or locate mates. But to unlock this information, ir sensory and nervous systems must be fast eugh to pick up and process se rapid changes in odour landscape.

speed of smell in animals and machines speed at which animals can detect and react to smells varies by species. Insects like grasshoppers and fruit flies process scent signals in just a few milliseconds, helping m move in and react to ir environments with ease. Mosquitoes can detect tiny bursts of carbon dioxide as short as 30 milliseconds, which is why y find you so easily at night.

Mammals were once thought to have slower smell detection, but recent studies have shown orwise. A landmark study in 2021 revealed mice could tell apart odours from mixed and separate sources in mere milliseconds. A paper published last month found that even humans can distinguish between different scents delivered just 60 milliseconds apart.

While fast odour sensors exist — devices such as photo-ionisation detectors — y are too bulky, power-hungry and often t selective eugh to be used in robots. device we developed w bridges this gap.

We found it could accurately identify odours in bursts as short as 50 milliseconds. Even more, it could decode patterns between odours switching up to 40 times per second, which is similar to what mice can do when y perform source-separation tasks. This means our device can “smell” at speeds that match those of animals.

electronic se is built on a multi-layer circuit board a little smaller than a credit card. It’s equipped with multiple metal-oxide gas sensors as well as temperature and humidity sensors.

What sets our device apart from ors is use of high-end electronics that can sample and control se sensors extremely fast and precisely, as well as custom-designed algorithms and processing methods.

sensors work by changing ir electrical properties based on how different gases react with an oxide layer on surface. A crucial part of making sensors so responsive is heating tiny sensing sites to several hundred degrees.

In turbulent air, sensor temperature tends to fluctuate, which makes odour detection and identification more difficult. By constantly measuring and re-justing temperature with a high level of precision, we achieved a highly sensitive sensor response that could detect even slight, fast changes in odours.

team also discovered that rapidly switching temperature back and forth between 150°C and 400°C about 20 times per second produced quick, distinctive data patterns that me it easier to identify specific smells. This approach allowed our device to pick up odours with remarkable speed and accuracy.

Applications and impact Equipping robots with fast odour sensors will allow m to detect and react to environmental cues in real time. This will enable more efficient navigation and decision making in challenging scenarios, opening doors for many promising applications.

For example, early detection of wildfires could save gigatonnes of carbon dioxide emissions. Conventional detection methods like satellites and planes only spot fires once y reach a significant size. Fires burning below forest capy or behind clouds can be missed entirely.

Drones equipped with fast electronic ses could change that by patrolling forests, identifying small plumes of smoke, n navigating towards and localising source. With this, large areas could be covered efficiently and fires detected before y grow out of control.

Ar critical application may be found in disaster response. After earthquakes or building collapses, finding survivors quickly is crucial.

Olfactory robots equipped with fast electronic ses could play a life-saving role by detecting unique scent signatures of humans trapped under debris. By rapidly scanning through complex environments and identifying human scent traces, se robots could guide rescue teams to victims faster than tritional methods, increasing chances of survival.

And for truffles? Perhaps one day, our robot could give truffle-hunting pigs a run for ir money, proving that even techlogy has a se for fine dining.