Yeast Biosensor Devised to Measure Radiation Exposure

Adding a drop of water to one of these badges activates yeast to show radiation exposure as read by an electronic device. (Kayla Wiles, Purdue University)

9 August 2018. An engineering group created a simple monitoring badge using yeast, which in a process similar to fermentation provides instant feedback on radiation exposure to lab workers. The radiation sensors, developed at Purdue University in West Lafayette, Indiana, are described in yesterday’s issue of the journal Advanced Biosystems (paid subscription required).

A team from Purdue’s Biomedical Microdevices Laboratory led by electrical and computer engineering professor Babak Ziaie is seeking a better process for measuring radiation exposure, which needs to be carefully monitored for people in work places such as medical offices and labs, where X-rays are routinely emitted. Even with protective gear, continuous low-level exposure can become dangerous, increasing the risk for cataracts, skin irritation, thyroid disease, and cancer.

Current devices called dosimeters can measure radiation exposure for radiology workers, but their data are usually read and compiled off-site and returned to the labs later on. “They wear the badges for a month or two” says Ziaie in a university statement, referring to radiology workers, “and then they send them to the company that made them. But it takes weeks for the company to read the data and send a report back to the hospital. Ours give an instant reading at much lower cost.”

The Purdue team’s sensor badge contains yeast, simple one-cell organisms used in baking and making beer. In this case, yeast provides living cells which react to radiation in predictable and measurable ways, since the organisms are also widely studied in labs as a model organism. In their badge-device, Ziaie and colleagues apply a film of yeast cells to a paper and aluminum surface. Exposure to radiation kills the yeast cells, something like the way human cells are damaged after extended exposure.

After worn for a period of time, the badge is put under a drop of water, which activates the remaining yeast cells. Wetting the yeast enables the cells to consume glucose and release carbon dioxide, similar to fermentation, but also generates ions that can be measured by attaching electrodes to the badge. The more exposure to radiation, the more yeast cells are destroyed, and the lower the amount of electrical energy produced by the badge.

Tests by the Purdue team show a small 18 by 18 millimeter badge can measure radiation doses as low as 1 millirad, or 0.001 rads, like today’s dosimeters. A rad is a standard measure of radiation dose exposure, with current OSHA guidelines calling for skin on a person’s body to be exposed to no more than 7.5 rads over a 3-month period.

The university filed for a patent on the device. The researchers are refining the technology to enable a smartphone or tablet app to read the badge and report the data. The team is also extending the technology for use in high radiation environments, such as nuclear power plants and radiation emergencies.

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