What if you could instantly diagnose diabetes, lung cancer or asthma just by blowing on a chip?

Scientists at the University of Florida in Gainesville have developed an infinitesimally tiny disposable sensor, costing just pennies, that might be able to do just that.

Fan Ren, a professor of materials science, engineering and computer engineering at the university, tells DOTmed News he and his team created the chip by joining sensing materials with a semiconductor transistor that ramps up the signal strength.

Ren's team includes Tanmay Lele, an assistant professor of chemical engineering, Jenshan Lin, a professor of electrical and computer engineering and Wenhsing Wu, a lecturer in electrical and computer engineering.

According to Ren, the device is one thousand to one million times more sensitive than conventional sensors, and works in less than 10 seconds. This extreme sensitivity lets it detect trace biomarkers of disease in body fluids, such as urine, saliva and even the condensed moisture of an exhaled breath.

BREATH TESTS

In the lungs, millions of tiny blood vessels get exposed to circulating gases, which pick up compounds found in the blood and carry them in our breath, Ren explains. Theoretically it should be possible for doctors to test for the same substances in the breath that they look for in blood.

But, in practice, it's tough. The problem with getting an accurate diagnosis from breath tests, Ren says, is that very little moisture comes from a breath condensate -- only around 4 micro liters, or one-hundredth the volume of a single drop of water.

While doctors have developed systems for, say, gathering glucose concentrations from breath tests, they're slow and cumbersome. For detecting glucose, it involves a complicated apparatus where patients have to breathe into a tube for a long time in order to collect enough material to make a diagnosis, says Ren.

"They need to collect a lot of samples, around 20 minutes to get enough breath condensate," he says.

But his device's sensitivity means it only needs 100 pico liters of condensate, so it can be processed nearly instantly.

Once the breath is collected and the substance is found by the sensor, it would automatically trigger a voltage discharge that could be controlled to give a read-out reporting the concentration level of the substance.

It would not need a specialized technician to read the results, Ren says.

FINDING DISEASE

Ren's team is already investigating the device's use in detecting lung cancer. To do so, the researchers coat sensors in antibodies that react to antigens produced by lung cancers and which travel in the breath.

Already, there is also interest in using the sensor to diagnose breast cancer by running saliva over it. Because of the antibodies used, the technology is only around 50 to 70 percent sensitive for breast cancer, and inferior to mammograms. But frequent testing produces a general trend that may alert doctors to the possibility that a patient has developed cancer.

Ren suggests this technology could be especially helpful in countries in the Middle East where taboos prevent women from getting timely tests. (See DM11427.)

"Over there, they do not have enough female doctors, so women seldom come out to do mammograms," he says. Because of the reluctance to get mammograms, 70 percent of women with breast cancer get diagnosed when the disease has spread to advanced stages with low five-year survival rates, according to Ren.

"With our technology, they can test this at home," he says. "Our sensor can be made for less than 20 cents. They can spit on it and throw it away."

MONITORING ASTHMA

The technology behind finding cancer could also catch respiratory diseases and monitor how successful therapies are in treating them. It would do this by measuring the pH of one's breath.

"Normally, it's 7 to 7.4, but when people have a serious asthma attack, the pH can drop to 5," Ren says. "If you can measure this, and you see the pH start to decrease to 6, [the patient] can take some medicine. If [the patient's] already sick and taking medicine, but they don't know whether it's working or not, the sensor can measure the pH variable."

TESTING THE WATERS

Direct medical testing is not the only way the device could protect people's health. It's also being used to keep track of contaminants in our waterways.

In last month's issue of Applied Physics Letters, researchers used Ren's device to investigate estrogen contamination in a Florida river where almost every fish became female. In the study, thanks to Ren's sensor, the scientists were able to detect large quantities of vitellogenin, a marker for estrogen exposure, in large mouth bass.

Next up, the researchers hope to see what the sex hormone pollution is doing to the region's manatee.

"This is a very powerful method," he says.

Currently, several companies are working with the University of Florida to license the technology for commercial use.