Schematic of a real-time in vitro fecal fermentation gas-sensing system. Credit: Nam Ha Microbes in the human body are estimated to outnumber human cells by 10 to 1, yet research on how they affect health is still in its infancy. A perspective article published by Cell Press on March 12th in Trends in Biotechnology presents evidence that gut microbes produce gases that may contribute to gastrointestinal diseases and could be used as biomarkers for one's state of health. As means to measure these potential biomarkers, the authors suggest two novel gas-sensing systems, one of which is an electronic gas sensor...