Exhaled-breath detection using AlGaN/GaN high electron mobility transistors integrated with a Peltier element

AlGaN/GaN high electron mobility transistors (HEMTs) integrated with a Peltier element are demonstrated for the detection of exhaled-breath condensate. The Peltier element mounted on the back side of the AlGaN/GaN HEMT was used to lower the temperature of the sensor in order to condense the exhaled breath. The measured cur-rent change shows that the pH of the condensate from the exhaled breath is within the range of 7-8, corresponding to the range of interest for human blood. The sensor exhibited a repeatable change of 1.24 mA/mm of the drain current at a drain bias of 0.25 V when the surface was exposed to repeated exhalations. This demonstrates the possibility of using AlGaN/GaN HEMT-based technology for the investigation of airway pathology. (c) 2007 The Electrochemical Society.