Described in a recent paper,* their electronic nose is more adept than conventional methodologies at recognizing molecular features even for 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.
The detector could be a potent tool for applications such as sniffing out nerve agents, environmental contaminants, and trace indicators of disease, in addition to monitoring industrial processes and aiding in space exploration.
In animals, 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. In humans, there are about 350 types of sensory neurons and many copies of each type; dogs and mice have several hundreds more types of sensory neurons than that. Odor recognition proceeds in a step-by-step fashion where the chemical identity is gradually resolved: initial coarse information (e.g. ice-cream is fruit-flavored vs. chocolate) is refined over time to allow finer discrimination (strawberry vs. raspberry). This biological approach inspired the researchers to develop a parallel “divide and conquer” method for use with the electronic nose.
The technology is based on interactions between chemical species and semiconducting sensing materials placed on top of MEMS microheater platforms developed at NIST. (See “NIST ‘Microhotplate’ May Help Search for Extraterrestrial Life,” NIST Tech Beat, Oct., 2001.) 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 at 350 temperature increments between 150 to 500 °C, increasing the number of sensors to about 5,600. The combination of the sensing films and the ability to vary the temperature gives the device the analytical equivalent of a snoot full of sensory neurons.
Much like people detect and remember many different smells and use that knowledge to generalize about smells they haven’t encountered before, the electronic nose also needs to be trained to recognize the chemical signatures of different smells before it can deal with unknowns. The great advantage of this system, according to NIST researchers Barani Raman and Steve Semancik, is that you don’t need to expose the array to every chemical it could come in contact with in order to recognize and/or classify them. Breaking the identification process down into simple, small, discrete steps using the most information rich data also avoids ‘noisy’ portions of the sensor response, thereby incorporating robustness against the effects of sensor drift or aging.
The researchers say that they are continuing to work on applications involving rapid identification of chemicals in unknown backgrounds or in a complex cocktail.
* B. Raman, J. L. Hertz, K. D. Benkstein and S. Semancik. Bioinspired methodology for artificial olfaction. Analytical Chemistry. Published online Oct. 15, 2008.
High-resolution version of image available at http://patapsco.nist.gov/ImageGallery/details.cfm?imageid=593
Mark Esser | Newswise Science News
New gene catalog of ocean microbiome reveals surprises
18.08.2017 | University of Hawaii at Manoa
Organ Crosstalk: Fatty Liver Can Cause Damage to Other Organs
18.08.2017 | Deutsches Zentrum für Diabetesforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Information Technology