Wearable 'microbreweries' track radiation exposure

Purdue University researchers have engineered yeast ‘microbreweries’ within disposable badges made of freezer paper, aluminium and tape, enabling a faster assessment of tissue damage that could lead to cancer. Just a drop of water can activate the yeast to show radiation exposure as read by an electronic device.

Radiology workers are currently required to wear badges, called dosimeters, on various parts of their bodies for monitoring their radiation exposure, said Babak Ziaie, Purdue professor of electrical and computer engineering. Workers wear the badges for a month or two, and then send them back to the manufacturer. The manufacturer usually takes weeks to read the data and send a report back to the hospital. “Ours give an instant reading at much lower cost,” said Ziaie.

“You would use the badge when you’re in the lab and recycle it after you’ve checked your exposure by plugging it into a device,” said Manuel Ochoa, a postdoctoral researcher in Purdue’s School of Electrical and Computer Engineering.

On a commercial level, the readout device could one day be a tablet or phone, according to Purdue. The badge could also be adapted in the future for nuclear power plant workers and victims of nuclear disasters.

The success of the badge is said to lie in the quick and measurable response of yeast to radiation — the higher the radiation dose, the higher the percentage of yeast cells that die. Wetting the badge activates the cells that are still alive to eat glucose and release carbon dioxide — the same fermentation process responsible for brewing beer and making bread rise.

When carbon dioxide bubbles at the surface, ions also form. The concentration of these ions increases the electrical conductivity of yeast, which can be measured by hooking up the badge to a readout system.

“We use the change in electrical properties of the yeast to tell us how much radiation damage it incurred. A slow decrease in electrical conductivity over time indicates more damage,” said Rahim Rahimi, Purdue postdoctoral researcher in electrical and computer engineering.

Numbers from the readout system translate to rads — the units used by entities like the Occupational Safety and Health Administration to specify limits on how much radiation human tissue can safely absorb. Skin of the whole body, for example, shouldn’t be exposed to more than 7.5 rad over a three-month period.

The researchers could detect a radiation dose as little as 1 millirad in the yeast badges, which is comparable to current commercial badges.

Yeast also is known to be genetically similar to human tissue. Data from the badges can, therefore, inform future work on how radiation damage happens to human DNA and proteins.

“For yeast, it seems that radiation primarily affects the cell walls of the membrane and mitochondria,” Ochoa said. 

Image credit: Purdue University image/Kayla Wiles.