Detection and quantification of nitric oxide in human breath using a semiconducting oxide based chemiresistive microsensor

Nitric oxide (NO) is recognized as playing a critical role in an ever-increasing list of diseases. An important requirement for more extensive utilization of the potential diagnostic value of NO concentrations in human breath is the development of low-cost, reliable NO monitoring devices. This paper describes a promising approach to meet this requirement using a semiconducting metal oxide based chemiresistive sensor. We have shown that it is possible to monitor NO levels in human breath samples with a WO3 based thin film chemiresistive sensor element. The sensor element is highly sensitive to nitrogen dioxide (NO2). Monitoring of NO is achieved via oxidation of the NO component in breath samples by an oxidizing agent such as alumina supported potassium permanganate (KMnO4). Human breath contains a large number of organic compounds that can interfere with the response of the sensor element as well as NO2. Molecular sieve filter materials such as silicalite are used to remove these interfering compounds from breath samples without affecting their NO concentrations. Verification of this monitoring scheme is demonstrated with data which correlates sensor response with NO concentrations in human breath samples, as determined by a chemiluminescence NO analyzer. (C) 2001 Elsevier Science B.V. All rights reserved.