Mater. Res. Soc. Symp. Proc. Vol. 1533 © 2013 Materials Research Society DOI: 1 557/op 013 0.1 l.2 . 3-sensor array for hand held breath diagnostic tool P. Gouma 1 , S. Sood 1 1 Department of materials science and engineering, Stony Brook University, Stony Brook, NY ABSTRACT Polymorphic transitions in nanocrystalline metal oxides leads to structural transformations resulting in differing properties at varying operating temperatures. Nanocrystalline MoO3 transforms from a metastable monoclinic phase to stable orthorhombic phase when heat treated in the temperature range of 420C to 500C. Gas sensing results have shown that at 420C MoO3 is sensitive to Isoprene, a 450C it shows sensitivity to CO2 and to ammonia at 500C. DSC data has proved that MoO3 changes crystal structure to monoclinic at 420C and to orthorhombic at about485C. This confirms a correlation between structure and gas sensing properties of MoO3. Using this knowledge a hand-held diagnostic tool is developed to monitor specific breath gases which can be biomarkers for diseases. The device consists of three sensors, the read-out gives a real time resistance value for each resistive sensor which is stored in a microprocessor. This is a one of a kind handheld tool for disease detection using ceramic sensors as detectors for gases which are known to be biomarkers for diseases. INTRODUCTION Breath tests for alcohol detections have been around for a while and breath analysis has been practiced since the time of Hippocrates (Fig. 1a). Our single breath portable breath analyzer concept is based on alcohol breath analyzers; the difference is that the latter use nonselective sensors based on tin dioxide, while ours utilizes other metal oxide nanostructures tailored to have specific affinity to the targeted gaseous biomarker. The added advantage is that our breath analyzers cost just as little as the alcohol ones, they will be available for over the counter purchase at a cost between US$50 and $200. In this paper we discuss one of a kind handheld tool for disease detection using ceramic sensors as detectors for gases which are known to be biomarkers for diseases. A single sensor breath-analysis tool has been successfully developed previously in authors lab[1,2]. Breath analysis will get closer to finding its place in the homecare market with our innovative products. The reported US $14 b market of point of care diagnostics in the US includes the US$7.7 billion market for homecare products, part of which are the existing self-diagnosis/monitoring devices. Our innovation (Fig. 1b) will open new markets as it offers new products such as the breath ammonia monitor for determining the endpoint of hemodialysis treatment. For this application, there are 1.3million patients worldwide receiving dialysis treatment and the number increases at a 7 % rate annually. Helping the suffering population monitor their treatment and ending it on time, by measuring the ammonia in exhaled breath in real-time during the process, 146