Health care: Disease breathalyzers

With new sensors, researchers are close to a breathalyzer that screens for illness.

Drunk drivers and dive-bar patrons have long been acquainted with the breathalyzer machine — a device that measures your blood-alcohol level when you breathe into it. But a team of researchers affiliated with the National Institute of Standards and Technology (NIST) in the U.S. is working to change disease diagnosis capabilities by developing a piece of technology that patients blow into, so a sensor can analyze the biomarkers in their breath — a breathalyzer that screens for illness.

Human noses can already do this on a very basic level with diabetes. Someone who is diabetic and deprived of insulin will expel air that smells like acetone when they are burning fat for energy. This can sometimes be detected on their breath by the sufferer and those close to them. Far more sensitive are dogs, whose sense of smell is so acute that they can be trained to detect the subtle scent of a cancer developing in the human body. This feat is possible because cancer cells emit a different kind of metabolic waste than healthy cells. These differences are called biochemical markers, and dogs can sniff them out in the parts-per-trillion range.

Carlos Martinez, a materials engineer and assistant professor at Purdue University in Indiana, says that the final goal of the project is to develop these disease breathalyzers to provide diagnostic and preventative screening for home or health-clinic use. But, before the sensors are ready for the market, Martinez and his four research partners must complete three key phases of development.

The first is to increase the sensitivity of the sensors they’ve developed to pick up on the subtle biomarkers. “The amazing thing about dogs is that they have so many sensors in their nose that they create a kind of fingerprint for smells. They are able to lock on to a smell, and I believe dogs are capable of the kind of detection we’re trying to do,” he says. Martinez estimates this development will take five more years to nail down.

The second phase is to develop algorithms to process the stream of data from the sensor. The final and most important stage is to develop a standard for what biometers constitute an illness. Altogether, Martinez estimates the technology is 10 years from becoming a reality.

That last step is the most important, but also one of the most challenging because “when you try to sample a large population of people who you already know have a certain disease, like cancer, it’s really difficult to pinpoint all the different biomarkers that will make you fairly sure of the person’s illness is detected regardless of environmental conditions,” he says. This is because a person living in the heavy smog of L.A. will have adapted to that environment and metabolize a different set of biomarkers than a rural dweller. “The accuracy you need before you can send the product to the market is high.”

The same sensors that can detect disease can also be used to do chemical warfare testing. In fact, all five of the researchers have worked for NIST in partnership with the Department of Homeland Security on these chemical micro-sensors.

For medical use, though, the device will also have to be mass-produced at an affordable price, and with compatibility to standard computers and cellphones, but Martinez is least worried about that. The chips they use in the sensors are very basic — similar to what would be found in a home computer.

Simplistic though the operating technology may be, the breathalyzer’s sensor would have a relatively short lifespan, and would need to be replaced after about a thousand uses. Martinez says that is because the device uses a porous structure to absorb the biometers in the gasses. In order to give an immediate and accurate reading, the sensor must be heated up. That process can only be repeated so many hundred times before it becomes unreliable.

But that increased cost will be offset by improved diagnostics. “Often, when doctors don’t know what’s wrong, they order a battery of tests. In some cases, they don’t find anything, and they have to test again. You can be doing that for months,” says Martinez. “Not only is the stress of the unknown hard, but it wastes money and time for the person and the hospital.” He says that having a single device to determine — or at least rule out — the disease in a non-invasive manner that delivers immediate results would have a huge impact on the patient and the entire medical system.