The experimental setup. (ETH Zurich/Simon Zogg)

In the future, breathalyzers will not just be used by police checking for alcohol intoxication, but also for testing the condition of athletes, and for people who want to lose weight. When exactly the body begins burning fat can now be determined by analyzing, for example, biomarkers in the blood or urine. Scientists have now developed a method for the real-time monitoring of lipolysis by testing a person’s exhalations during exercise.

The sensor developed uses a chip coated with a porous film of special semiconducting nanoparticles. The particles are tungsten trioxide implanted with single atoms of silicon. The goal is to offer the chip in a manageably sized device. The scientists are also working on developing gas sensors for other medically relevant molecules in exhalations.