Hand-Held Breathalyzer Aids Diabetes Diagnosis

Exhaled acetone from breath is released into the optical cavity, where it is probed by a near-infrared (NIR) diode laser operating at ∼1670 nm.

As the optical cavity mirror has a reflectivity of 99.994%, breath-sampling rates have a precision of 100 parts per billion by volume (PPBV). The researchers validated the device with measurement of exhaled breath in healthy subjects under different conditions, such as after overnight fasting or exercising, and compared the results with mass spectrometry readings. The measurements were a close match and covered a wide range of concentrations, including those that would suggest a patient has undiagnosed type-1 diabetes. The study was published on October 18, 2016, in Analytical Chemistry.

“It was not an easy task, because breath contains molecules of millions of compounds while this test requires detecting only one of them,” said Ian Campbell, CEO of Oxford Medical Diagnostics. “So, what we do is allow the subject to blow into the device, we extract out the volatile organic compound we wish to measure, in this case acetone. The remainder of the breath passes through the device. We then release the molecules that we're interested in into the cavity to make the measurement.”

The new method is based on cavity ringdown spectroscopy, a method that is used to detect volatile organic compounds (VOCs) released from human breath or skin. It is grounded on the premise that those with diabetes exhale elevated levels of acetone, resulting from ketoacidosis. When classified as diabetic ketoacidosis, the high concentration of ketone bodies is usually accompanied by insulin deficiency, hyperglycemia, and dehydration. The problem is that detecting the acetone is difficult because different compounds, including water, CO2, and methane, compromise the results.

Related Links:
University of Oxford
Oxford Medical Diagnostics