Sensors based on functionalized carbon nanotube field effect transistors have already shown great promise. They combine high sensitivity due to the reduced dimensionality and exceptional electronic properties of the nanotubes with high molecular affinity, conferred by surface functionalization with biomolecules such as single-stranded DNA. Here we show that dilute vapors of volatile organic compounds can be reliably detected down to part-per-billion concentrations. We extend this work by studying vapors from complex fluids of human origins, including sweat and blood. Synthetic versions of these fluids are also used to test the ability of the devices to differentiate solutions that are extremely similar but differ in a known way. We show that the devices are able to detect changes in the concentration of one compound, at part-per-billion levels, even in a background of many similar compounds. This opens up the tantalizing possibility of tracking volatile biomarkers in bodily fluids quickly and cheaply using a solid state sensor, which could have a huge impact in medical diagnostics.
This research was supported by the Department of Defense US Air Force Research Laboratory and UES through Contract Nos. FA8650-09-D-5037 as well as support from the Army Research Office through grant #W911NF-11-1-0087.