Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Portable and precise gas sensor could monitor pollution and detect disease

22.09.2009
In the air, it is a serious pollutant. In the body, it plays a role in heart rate, blood flow, nerve signals and immune function.

Nitric oxide, a gas well known to scientists for its myriad functions, has proven challenging to measure accurately outside the laboratory.

A team of Princeton and Rice University researchers has demonstrated a new method of identifying the gas using lasers and sensors that are inexpensive, compact and highly sensitive. Such a portable device, suitable for large-scale deployment, could be of great value to atmospheric science, pollution control, biology and medicine.

Nitric oxide is so potent that a few molecules of it per billion, or even trillion, molecules of air promote smog, acid rain and depletion of the ozone layer. Similarly tiny amounts in a patient's breath could help diagnose asthma and other disorders.

The researchers believe their device could find uses ranging from the study and control of car and truck emissions to monitoring human exposure to pollutants in urban and industrial environments. For medical uses the device is particularly attractive because the results are not corrupted by water vapor, which is present in breath samples. Testing for nitric oxide in a patient's breath, for example, could reveal chronic obstructive pulmonary disease and inflammation.

"The sensor we've developed is much more accurate and sensitive than existing systems, yet is far more compact and portable," said Gerard Wysocki, assistant professor of electrical engineering at Princeton.

Wysocki is a co-leader of a team that developed the system and conducted preliminary tests during the 2008 Olympic Games in Beijing. The team included Rice researchers Frank Tittel and 1996 Nobel laureate Robert Curl, both pioneers in the field of molecular detection using lasers, as well as Rafa³ Lewicki and James Doty III, also of Rice. The team published its results in the Aug. 4 issue of the Proceedings of the National Academy of Sciences.

With improvements made after the Beijing test, the system could be made into a portable, shoe-box-sized device ideally suited for mass deployment in large-scale unattended sensor networks for global, real-time, continuous monitoring of nitric oxide and other gases present in trace amounts.

Existing systems to detect nitric oxide and other trace gases have a variety of drawbacks. Some, such as carbon monoxide sensors for homes, are compact and inexpensive, but not very sensitive. These sensors can at best detect gases at parts-per-million concentrations -- they can't handle the parts-per-billion level, let alone the parts-per-trillion level that some applications require. High-end systems, such as mass spectrometers and gas chromatographs, are much more sensitive, but are slow, bulky, complicated and expensive -- and impractical for use outside of a lab.

Of intermediate sensitivity are optical systems that pass a laser beam through a gas sample and detect whether some of the laser light is absorbed by the gas sample. A weakness of this method is that the amount of absorption is very small compared to the overall amount of laser light, so the signal is hard to detect. Further, conventional optical sensors tend to be bulky, use large amounts of the sample, and require frequent operator intervention.

The new system developed by Princeton and Rice researchers uses optical sensing as well, but produces a much stronger signal. In their setup, the researchers passed the laser light through polarizing filters that block all light unless nitric oxide is present. Roughly speaking, the more nitric oxide, the more light makes it through the filters, Wysocki said. "There's no background signal to worry about."

Nitric oxide detectors have used similar methods before, but until now have been hampered by their reliance on large laser sources designed for laboratory use, he said. The new system, in contrast, uses a quantum cascade laser, a state-of-the-art device ideally suited for this sensing technique. This makes it possible to reliably detect the gas at a concentration of a few parts-per-billion. The device is so precise it can distinguish between different isotopes of nitrogen and oxygen in the nitric oxide molecules.

"It's remarkable we have that kind of sensitivity," said Curl, who laid the groundwork for the detection technique in a paper he co-wrote with Tittel nearly 30 years ago.

"A portable sensor that can continuously measure nitric oxide with such high sensitivity is a real breakthrough," said Tittel.

Unlike other systems that need several liters of the sample gas, the new sensor needs only a few milliliters of it, inside a container just about 16 inches long and a half inch in diameter. This frugality is particularly important in delicate biological applications such as cell-culture studies, said Wysocki. Also important, the new system can run much longer without intervention -- several hours compared to just a few minutes for even the best existing ones -- which will allow for long-term unattended operation.

Princeton researchers are working on various enhancements to the technology, further shrinking the size of the device and exploring an even more sensitive method of analysis called coherent detection. "This technique could help us achieve parts-per-trillion sensitivity," Wysocki said.

The work was supported by the National Science Foundation through a larger grant to the MIRTHE (Mid-InfraRed Technologies for Health and the Environment Engineering) Research Center based at Princeton, and by the Department of Energy as part of larger grants from Aerodyne Research Inc. and the Robert Welch Foundation.

Steven Schultz | EurekAlert!
Further information:
http://www.princeton.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

Im Focus: Quantum-physical Model System

Computer-assisted methods aid Heidelberg physicists in reproducing experiment with ultracold atoms

Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...

Im Focus: Glacier bacteria’s contribution to carbon cycling

Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.

A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

New quantum liquid crystals may play role in future of computers

21.04.2017 | Physics and Astronomy

A promising target for kidney fibrosis

21.04.2017 | Health and Medicine

Light rays from a supernova bent by the curvature of space-time around a galaxy

21.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>