Cancer detection: The development of a cost-effective, portable and non-invasive diagnostic tool for detecting cancer from exhaled breath requires sensors that discriminate well between polar and nonpolar volatile organic compounds in highly humid atmospheres. Here we show that a chemiresistive bilayer comprised of a dense cap layer of discotic hexa-dodecyl-hexa-peri-hexabenzocoronene derivatives (hereby, HBC-C12) and a random network of carbon nanotubes (RN-CNT) as underlayer layer could fulfill these requirements.