The yield of individual In2O3 nanowire or carbon nanotube devices can be controlled by adjusting the nanowire / nanotube density. We can typically produce ten such devices on one chip, which could be sufficient for clinic diagnosis applications. In contrast, the carbon nanotube mat devices (Figure 3b inset) have a yield close to 100%, as synthesis of nanotube mat is highly reproducible, and patterning of the source / drain electrodes can be easily done using photolithography without any alignment. We note that alternative approaches using vertical multiwalled carbon nanofibers [Ref 4] can provide devices with high yield and very high sensitivity, though these sensors are based on the electrochemical response of biomolecules, as compared to the chemical gating mechanism employed by our nanowire / nanotube field effect sensors.