UV-activated ZnO/CdO n-n isotype heterostructure as breath sensor

The demand for developing a non-invasive sensor towards disease diagnosis such as diabetes, renal dysfunction, and cancer has been increasing tremendously. The presence of biomarkers such as ammonia, acetone, and ethanol in human exhaled breath indicates the onset of various diseases. In this context, the present investigation is focused on developing a cost-effective acetone sensor using isotype ZnO/CdO heterostructure thin film by spray pyrolysis technique. The sensing signatures of the heterostructure was examined in the presence of light activation using UV LED light. Structural analysis of the heterostructure divulged the growth of cubic phased CdO and hexagonal phased ZnO crystallites towards (1 1 1) and (1 0 1) planes respectively. Spin-orbit splitting of Cd( )3d subshells was confirmed through the surface analysis. The heterostructure showed selective photo-response of 540 towards acetone at room temperature. Response and recovery times were observed as 61 and 47 s respectively towards 1 ppm of acetone vapor. The linear detection range of the sensor was observed to be 1-100 ppm with long-term stability. Since the sensor showed the lowest detection limit of 1 ppm, the sensor can be used for the identification of acetone from exhaled breath for disease diagnosis. (C) 2019 Elsevier B.V. All rights reserved.