Researchers at the National Institute of Standards and Technology (NIST) have developed a new approach for “electronic noses.” The new noses are comprised of 16 microheater elements and eight types of sensors with a pattern-recognition module that mimics the way animals recognize odors. This tiny device could be a potent tool for applications such as sniffing out nerve agents, environmental contaminants, and trace indicators of disease such as cancer, in addition to monitoring industrial processes and aiding in space exploration.
This new electronic nose is more adept than conventional technologies at recognizing molecular features even of chemicals it has not been trained to detect and is also robust enough to deal with changes in sensor response that come with wear and tear.
Odorant molecules in the air enter the nostrils and bind with sensory neurons in the nose that convert the chemical interactions into an electrical signal that the brain interprets as a smell. While humans only have about 350 types of sensory neurons and many copies of each type, dogs and mice have at least several hundred more types of sensory neurons and are much more sensitive to odors than humans. Odor recognition proceeds in a step-by-step fashion in which the chemical identity is gradually resolved: initial coarse information is refined over time to allow finer discrimination, which inspired the researchers to develop a parallel “divide and conquer” method for use with the electronic nose.
The electronic nose employed in the current work is comprised of eight types of sensors in the form of oxide films deposited on the surfaces of 16 microheaters, with two copies of each material. Precise control of the individual heating elements allows the scientists to treat each of them as a collection of “virtual” sensors, increasing the number of sensors to about 5,600. People can detect and remember many different smells, and they use that familiar knowledge to generalize about smells they haven’t previously encountered. Similarly, the electronic nose can also be trained to recognize the chemical signatures of different smells before it deals with unknown ones, so that there is no need to expose the array to every chemical it could come in contact with in order to recognize and/or classify them. Meanwhile, researchers are continuing to work on applications involving rapid identification of chemicals in unknown backgrounds or in a complex cocktail.
TFOT previously covered a different electronic nose developed by researchers from the university of Warwick and Leicester in the U.K. The nose uses a mix of polymers that mimics the action of the mucus in the natural nose allowing it to pick out a more diverse range of smells.
You can read more about the new electronic nose on the NIST website.