Your breath holds the key to monitoring fat burning, and now a research group from Tohoku University has created a compact and low-cost device that can measure how our body metabolizes fat.

The device uses an ultraviolet lamp to gauge exhaled acetone gas, which is produced in the blood through the metabolic reaction of fat.

"Precise measurements of acetone gas concentration allows us to determine the body's ability to metabolize fat and develop exercise methods for efficient fat burning," says Professor Yuji Matsuura from Tohoku University's Graduate School of Biomedical Engineering, who led the research group.

The details of their study were published in the journal Sensors on January 12, 2021.

Matsuura and his team focused on ultraviolet light, which due to its extremely short wavelength is strongly absorbed by acetone gas. They succeeded in measuring the acetone concentration with high accuracy: 0.03 ppm--while the acetone concentration is about 1 ppm in exhaled air. To do this, they trapped exhaled air in a thin tubular optical fiber--called a hollow optical fiber--that had been exposed to vacuum ultraviolet light produced from an ultraviolet lamp. The group measured the degree to which the light is weakened as a result of the absorption of acetone gases to ascertain the acetone gas concentration.