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Nanoscale Techniques Drive Real-Time Biomarker ‘Breathalyzer’

by Editor1 last modified January 22, 2011 - 11:37

Researchers using nanoparticle technologies and sensors have demonstrated a super real-time breathalyzer that is 100 times more sensitive than today’s devices, and promises advances in the ability to diagnose illness with only a patient’s breath. The work was done by the National Institute of Standards and Technology and Purdue University.

Nanoscale Techniques Drive Real-Time Biomarker ‘Breathalyzer’

NIST and Purdue Researchers demonstrate real-time breathalyzer to detect biomarkers of disease.

The breakthrough overcomes a long-standing obstacle to using breath-analysis technology for real-time diagnosis, researchers said.

The approach centers on detecting chemical biomarkers – or compounds in a person's respiration. The device can detect biomarkers in real-time in concentrations as small as parts per billion (ppb), according to Carlos Martinez, an assistant professor of materials engineering at Purdue working with NIST researchers.

"People have been working in this area for about 30 years but have not been able to detect low enough concentrations in real time," Martinez said in a statement. "We solved that problem with the materials we developed, and we are now focusing on how to be very specific, how to distinguish particular biomarkers."

The key to the NIST/Purdue project came as researchers used nano-coated microparticles instead of a flat surface. This design increases sensitivity by allows researchers to increase the porosity of the sensor films and boost the active sensing surface area.

"We are talking about creating an inexpensive, rapid way of collecting diagnostic information about a patient," Martinez said. "It might say, 'there is a certain percentage that you are metabolizing a specific compound indicative of this type of cancer,' and then additional, more complex tests could be conducted to confirm the diagnosis."

The team used a template made of micron-size polymer particles and coated them with far smaller metal oxide nanoparticles. This design provided the ability to detect changes in electrical resistance (or what researchers call ‘conductance’) as gases pass over sensors.

For sensitivity, the sensors are built on top of the device’s microhotplates, which are tiny heating devices about 100 microns square and placed on electronic chips.

Inside the NISST/Purdue
Nano-Based Real-Time Breathalyzer
During the test operations, a droplet of the nanoparticle-coated polymer microparticles was deposited on each microhotplate, which contains electrodes shaped like meshing fingers. The droplet dries and then the electrodes are heated up, burning off the polymer and leaving a porous metal-oxide film, creating a sensor.

The researchers used the technology to detect acetone, a biomarker for diabetes, with a ppb sensitivity in gas which mimicked a person's breath. Gases passing over the device permeate the film and change its electrical properties depending on the particular biomarkers contained in the gas. From a practical standpoint, these breathalyzers are likely a decade or more away, Martinez said, in large part because of an absence of precise standards. "However, the fact that we were able to do this in real time is a big step in the right direction," he added.

The findings appeared in the IEEE Sensors Journal, published by the Institute of Electrical and Electronics Engineers' IEEE Sensors Council. The paper was co-authored by Martinez and NIST researchers Steve Semancik, lead author Kurt D. Benkstein, Baranidharan Raman and Christopher B. Montgomery.