Electronic noses might replace search-and-rescue dogs | Science News for Students

Electronic noses might replace search-and-rescue dogs

A powerful new sensor can sniff out people trapped in collapsed buildings
Jun 25, 2018 — 6:45 am EST
search dog

After a disaster, search-and-rescue dogs use their amazing sense of smell to search for trapped people. But could an e-nose do their job for them? This pooch is looking over its shoulder.

Sgt. Kyle Brasier/Dept. of Defense

After a disaster, search-and-rescue dogs use their amazing sense of smell to search for trapped people. But could an e-nose do their job for them? This pooch is looking over its shoulder.

Sgt. Kyle Brasier/Dept. of Defense

Dogs are some of our best friends. That’s especially true after a disaster, such as an earthquake. When buildings collapse, search-and-rescue dogs help find people trapped beneath the rubble. Dogs’ amazing noses can pick up the scent of survivors. Now scientists have developed an electronic tool that does the same thing. It’s taking scent detection to a whole new level — or, should we say, to extremely low levels.

a gas sensor
Sensors in the new device are made of a material that detects a certain chemical. When that target chemical contacts the sensor, a reaction occurs. This creates an electrical signal.
S. Pratsinis/Swiss Federal Institute of Technology

The new device is a sort of electronic nose. Much like the canine version, this e-nose can detect chemical signs of life. Such scents include those due to acetone (AA-sih-tohn), ammonia (Uh-MOHN-yuh), isoprene (EYE-soh-preen), water vapor and carbon dioxide. People exhale tiny amounts of these or release them from their skin.

Researchers in Europe developed a device that can detect extremely low levels of these compounds. The tool includes three sensors the group designed, and two more that they bought. When certain chemicals touch materials on the sensors, a reaction occurs. This reaction produces an electrical signal. When occurring together, even tiny amounts of these compounds could point to some survivor below the rubble.

The research team described its findings March 30 in the journal Analytical Chemistry.  

The e-nose knows

This isn’t the first time engineers have developed such a device. Earlier models, however, have been bulky and expensive. They could not detect low levels of target compounds either.

The new sensors are inexpensive and small enough to fit inside a handheld device. A drone might even fly them over a disaster site.

The device can detect incredibly faint traces of more than one compound at the same time. “Being able to do this, in such a small device, is the critical discovery,” says Sotiris Pratsinis. He’s a chemical engineer with the Swiss Federal Institute of Technology in Zurich. Pratsinis helped create the gadget.

His team tested it in chambers with people inside. Those chambers were like the small spaces in rubble where people might be trapped. Chemicals given off by the volunteers built up inside the chambers. The new device detected those compounds at incredibly low levels.

Story continues below video.

Scientists have been developing electronic noses that are capable of detecting many different odors — even those associated with disease. Watch this video to find out how they work.
Universitat Rovira i Virgili/YouTube

A sniffing team

The results were good news for the research team. But they might not be such good news for our four-legged friends, who could soon be out of a job. “Ideally, this technology could replace search-and-rescue dogs,” Pratsinis says.

Stephen Taylor agrees that the new technology has some benefits over dogs. For example, dogs need to take breaks. And they might not always be available when disasters strike. Taylor is an electrical engineer at the University of Liverpool in England.

He suspects the new device could improve how rescuers find disaster survivors. Still, he thinks it may be too soon to retire our trusty search-and-rescue pooches. Dogs and the electronic devices could work together, he suspects: “I foresee that such a sensor could add to the fine work done by sniffer dogs.”

Taylor also pointed out some potential limitations of the chemical sensors. “E-noses are useful. But they can be prone to unstable readings and interference,” he says. Researchers will need to test e-noses outside the lab to make sure they’re reliable.

Pratsinis plans to fine-tune his device by testing it in simulated disaster zones. He also thinks that with tweaks, his team’s device could detect the characteristic gases emitted by a corpse. Then the tool could tell whether a disaster victim is still alive. Knowing that could help rescuers target their initial efforts on survivors.

Rescue dogs already can sniff out live people who are trapped. Other dogs can detect cadavers. In each case, training dogs to know these scents takes time and money. Someday, e-noses might replace the wet noses of search-and-rescue dogs. Until then, when disasters strike, such electronic devices could team up with those canines to home in on survivors.

Why do dogs have such an amazing sense of smell? Watch the video to find out.
PBS News/YouTube

Power Words

(more about Power Words)

acetone     A chemical produced by the body that is detectable in people’s breath. It’s also an extremely flammable liquid solvent used, for example, in nail polish remover.

ammonia     A colorless gas with a nasty smell. Ammonia is a compound made from the elements nitrogen and hydrogen. It is used to make food and applied to farm fields as a fertilizer. Secreted by the kidneys, ammonia gives urine its characteristic odor. The chemical also occurs in the atmosphere and throughout the universe.

analytical     chemistry A field that focuses on ways to separate materials into their parts or elements.

canine     Members of the biological family of canids. These are carnivores and omnivores. The family includes dogs, wolves, foxes, jackals and coyotes. 

carbon     The chemical element having the atomic number 6. It is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

carbon dioxide (or CO2)    A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. Carbon dioxide also is released when organic matter burns (including fossil fuels like oil or gas). Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chemical engineer     A researcher who uses chemistry to solve problems related to the production of food, fuel, medicines and many other products.

chemistry     The field of science that deals with the composition, structure and properties of substances and how they interact. Scientists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances.

compound     (often used as a synonym for chemical) A compound is a substance formed when two or more chemical elements unite (bond) in fixed proportions. For example, water is a compound made of two hydrogen atoms bonded to one oxygen atom. Its chemical symbol is H2O.

drone     A remote-controlled, pilotless aircraft or missile.

earthquake     A sudden and sometimes violent shaking of the ground, sometimes causing great destruction, as a result of movements within Earth’s crust or of volcanic action.

engineering     The field of research that uses math and science to solve practical problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need. People who work in this field are also known as engineers.

federal     Of or related to a country’s national government (not to any state or local government within that nation). For instance, the National Science Foundation and National Institutes of Health are both agencies of the U.S. federal government.

journal     (in science) A publication in which scientists share their research findings with experts (and sometimes even the public). Some journals publish papers from all fields of science, technology, engineering and math, while others are specific to a single subject. The best journals are peer-reviewed: They send all submitted articles to outside experts to be read and critiqued. The goal, here, is to prevent the publication of mistakes, fraud or sloppy work.

model     A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes. Or an individual that is meant to display how something would work in or look on others.

sensor     A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.

tune     (in engineering) Adjust to the right level.

water vapor     Water in its gaseous state, capable of being suspended in the air.


Journal: A.T. Güntner et al. Sniffing entrapped humans with sensor arrays. Analytical Chemistry. Vol. 90, March 30, 2018. p. 4940. doi: 10.1021/acs.analchem.8b00237.