|Electronic Nose Sniffs out Toxins
Imagine a polka-dotted postage stamp-sized sensor that can sniff
out some known poisonous gases and toxins and show the results
simply by changing colors.
Support for the development and application of this electronic
nose comes from the National Institute of Environmental Health
Sciences, part of the National Institutes of Health. The new technology
is discussed in this month's issue of Nature Chemistry and exemplifies
the types of sensors that are being developed as part of the NIH
Genes, Environment and Health Initiative (GEI) (http://www.gei.nih.gov/index.asp).
Once fully developed, the sensor could be useful in detecting
high exposures to toxic industrial chemicals that pose serious
health risks in the workplace or through accidental exposure. While
physicists have radiation badges to protect them in the workplace,
chemists and workers who handle chemicals do not have equivalent
devices to monitor their exposure to potentially toxic chemicals.
The investigators hope to be able to market the wearable sensor
within a few years.
"The project fits into the overall goal of a component of
the GEI Exposure Biology Program that the NIEHS has the lead on,
which is to develop technologies to monitor and better understand
how environmental exposures affect disease risk," said NIEHS
Director Linda Birnbaum, Ph.D. "This paper brings us one step
closer to having a small wearable sensor that can detect multiple
The paper's senior author is Kenneth S. Suslick, Ph.D., the M.T.
Schmidt Professor of Chemistry at the University of Illinois at
Urbana-Champaign. Suslick and his colleagues have created what
they refer to as an optoelectronic nose, an artificial nose for
the detection of toxic industrial chemicals (TICs) that is simple,
fast, inexpensive, and works by visualizing colors.
"We have a disposable 36-dye sensor array that changes colors
when exposed to different chemicals. The pattern of the color change
is a unique molecular fingerprint for any toxic gas and also tells
us its concentration," said Suslick. "By comparing that
pattern to a library of color fingerprints, we can identify and
quantify the TICs in a matter of seconds."
The researchers say older methods relied on sensors whose response
originates from weak and highly non-specific chemical interactions,
whereas this new technology is more responsive to a diverse set
of chemicals. The power of this sensor to identify so many volatile
toxins stems from the increased range of interactions that are
used to discriminate the response of the array.
To test the application of their color sensor array, the researchers
chose 19 representative examples of toxic industrial chemicals.
Chemicals such as ammonia, chlorine, nitric acid and sulfur dioxide
at concentrations known to be immediately dangerous to life or
health were included. The arrays were exposed to the chemicals
for two minutes. Most of the chemicals were identified from the
array color change in a number of seconds and almost 90 percent
of them were detected within two minutes.
The laboratory studies used inexpensive flatbed scanners for imaging.
The researchers have developed a fully functional prototype handheld
device that uses inexpensive white LED illumination and an ordinary
camera, which will make the whole process of scanning more sensitive,
smaller, faster, and even less expensive. It will be similar to
a card scanning device.
"One of the nice things about this technology is that it
uses components that are readily available and relatively inexpensive," said
David Balshaw, Ph.D., a program administrator at the NIEHS. "Given
the broad range of chemicals that can be detected and the high
sensitivity of the array to those compounds, it appears that this
device will be particularly useful in occupational settings."
|A postage stamp sized
optical sensor array (small square silver colored device)
for toxic gases and the sampled color changes associated
with a few representative poison gases (chlorine, fluorine,
hydrofluoric acid, hydrogen cyanide, B2H2, hydrazine, cobalt
chloride, H2S, phosphine, ammonia, NO2, and sulphur dioxide).
The NIEHS supports research to understand the effects of the environment
on human health and is part of NIH. For more information on environmental
health topics, visit our Web site at http://www.niehs.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and Centers
and is a component of the U.S. Department of Health and Human Services.
It is the primary federal agency for conducting and supporting basic,
clinical and translational medical research, and it investigates
the causes, treatments, and cures for both common and rare diseases.
For more information about NIH and its programs, visit www.nih.gov.
Reference(s): Lim SH, Feng L, Kemling JW, Musto
CJ, Suslick KS. 2009. An Optoelectronic Nose for Detection of Toxic
Gases. Nature Chemistry. Published Online in Advance of
Print. DOI: 10.1038/NCHEM.360.