Scientists have developed a method for real-time monitoring of lipolysis (breakdown of lipids) by testing a person’s exhalations during exercise. In other terms, it’s a breath sensor that can detect when the body is burning fat. The researchers reported their findings in the journal Analytical Chemistry.
“When burning fat, the body produces by-products that find their way into the blood,” explains Andreas Güntner, a postdoc in the group of Sotiris Pratsinis at ETH Zurich. Biomarkers in the blood or urine, for example, can indicate when the body begins burning fat.
Güntner and his colleagues have developed a small gas sensor that measures the presence of acetone, which is a volatile lipid metabolite that enters the air that the person exhales.
The new sensor can detect a single acetone molecule in a hundred million, so other molecules do not affect the measurement.
The sensor developed by the scientists uses a chip coated with a porous film of special semiconducting nanoparticles. The particles are tungsten trioxide that the researchers have implanted with single atoms of silicon.
Development of the chip began seven years ago when Pratsinis and his colleagues discovered that tungsten trioxide nanoparticles interact with acetone if the atoms of the nanoparticles are arranged in a certain crystalline structure. The interaction reduces the electrical resistance of the chip coated with the nanoparticles, and this phenomenon can then be measured.
Low cost, small size
Highly sensitive acetone measurements already exist in the market. For example, mass spectrometers, which are large laboratory devices that cost several hundred thousand Swiss francs. As well as portable acetone breath tests, but they can only be used once and take several minutes before they show the results.
“Our technology has the major benefit of being inexpensive, manageable, and yet highly sensitive—plus it can take measurements in real time,” says Güntner. “This makes it suitable for everyday use, while working out at a fitness center or for people on a diet.”
The scientists are also working on developing gas sensors for other medically relevant molecules in exhalations, including ammonia to test kidney function, isoprene to test cholesterol metabolism, and various aldehydes for the early detection of lung cancer.