Engineers Develop Biomarker Breathalyzer Diagnostics

Breathalyzer template (Purdue Univ./NIST)

Researchers at Purdue University in West Lafayette, Indiana are developing breath-analysis technology to diagnose patients in real time by detecting chemical compounds called biomarkers in a person’s respiration. Carlos Martinez, an assistant professor of materials engineering leads the project for Purdue, and is working with colleagues at the National Institute of Standards and Technology, a division of the U.S. Department of Commerce.

Martinez says the team demonstrated that its approach can detect biomarkers in the parts per billion to parts per million range, at least 100 times better than previous breath-analysis technologies. 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.

The researchers used a template (pictured right) 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 sensing area to improve sensitivity. A micron or micrometer is one millionth of a meter; a nano or nanometer is one billionth of a meter.

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. Gases passing over the device permeate the film and change its electrical properties depending on the particular biomarkers contained in the gas.

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. Their findings were published in a research paper that appeared earlier this year in the IEEE Sensors Journal (paid subscription required).

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