Almost a century after telephone pioneer Alexander Graham Bell first popularized the idea of measuring smells, chemical vapor sensors - \"electronic noses\" - are being developed for use in diagnosing disease, detecting national security threats, and other futuristic uses. A new episode in the American Chemical Society\'s (ACS) award-winning Bytesize Science series takes viewers on a behind-the-science tour of a major lab that is developing affordable, easy-to-carry chemical vapor detection systems. McCaig likens chemical vapor sensors to the old-fashioned canary-in-a-cage, once used to determine whether methane or other potentially dangerous gases has seeped into a coal mine, noting that some can sniff out hazardous substances undetectable by human noses. These e-noses have potential applications in public safety as bomb or toxic substance detectors. In the future, they might even go into general use in early diagnosis of disease by detecting telltale signs of tuberculosis, lung cancer and other disorders on a patient\'s breath.