This image shows a new type of sensor for an advanced breath-analysis technology that rapidly diagnoses patients by detecting “biomarkers” in a person’s respiration in real time. Researchers used a template made of micron-size polymer particles and coated them with much smaller metal oxide nanoparticles. Using nanoparticle-coated microparticles instead of a flat surface allows researchers to increase the porosity of the sensor films, increasing the “active sensing surface area” to improve sensitivity. (Purdue Univ. and NIST)
Researchers have overcome a fundamental obstacle in
developing breath-analysis technology to rapidly diagnose patients by detecting
chemical compounds called “biomarkers” in a person’s respiration in
The researchers demonstrated their approach is capable of
rapidly detecting biomarkers in the parts per billion to parts per million
range, at least 100 times better than previous breath-analysis technologies,
said Carlos Martinez, an assistant professor of materials engineering at Purdue
who is working with researchers at the National Institute of Standards and
“People have been working in this area for about 30
years but have not been able to detect low enough concentrations in real
time,” he said. “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 technology works by detecting changes in electrical
resistance or conductance as gases pass over sensors built on top of
microhotplates, tiny heating devices on electronic chips. Detecting biomarkers
provides a record of a patient’s health profile, indicating the possible
presence of cancer and other diseases.
“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 researchers used the technology to detect acetone, a
biomarker for diabetes, with a sensitivity in the parts per billion range in a
gas mimicking a person’s breath.
Findings were detailed in a research paper that 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.
The researchers used a template made of micron-size
polymer particles and coated them with far smaller metal oxide nanoparticles.
Using nanoparticle-coated microparticles instead of a flat surface allows
researchers to increase the porosity of the sensor films, increasing the
“active sensing surface area” to improve sensitivity.
A droplet of the nanoparticle-coated polymer
microparticles was deposited on each microhotplate, which are about 100 microns
square and contain 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.
“It’s very porous and very sensitive,” Martinez said. “We
showed that this can work in real time, using a simulated breath into the
Gases passing over the device permeate the film and change
its electrical properties depending on the particular biomarkers contained in
Such breathalyzers are likely a decade or longer away from
being realized, in part because precise standards have not yet been developed
to manufacture devices based on the approach, Martinez said.
“However, the fact that we were able to do this in
real time is a big step in the right direction,” he said.