You may have an illness and not even know it—and the proof could be on your breath. That's because our bodies give off complex aromas, some too faint for a human nose. And when sickness alters cell metabolism, an array of telltale volatile chemicals make their way into our breath, urine, and sweat. Now, research labs around the world are figuring out how to use gas sensors to detect disease. Here are a few ailments they've gotten a whiff of so far.
Detection: A grid of gold nanoparticles, each with different chemiresistive organic coatings. Certain volatile chemicals cause the sensor's particles to swell, changing their electrical resistance and allowing scientists to identify signs of cancer on a patient's breath.
Detection: Gas chromatography/mass spectrometer. The instrument can spot markers of runaway oxidation in a pregnant woman's body, an indicator of preeclampsia.
Detection: Ion trap mass spectrometer. If someone is certifiably nuts, their breath may have notes of ether and pentane, according to one study. Unfortunately pentane appears in high levels with all sorts of disorders, so it's not a reliable marker.