Au nanoelectrodes for breath analysis

M. Righettoni, A. Tricoli, S.E. Pratsinis
ETH Zurich, CH

Keywords: breath analysis, nanoparticles, gas sensor

Summary:

New medical diagnostic methods such as non-invasive human breath analysis bear the potential of drastically reducing medical costs as a greater amount of automatization is possible. SnO2 is one of the most utilized and best understood prototype gas sensor. It has high sensitivity to several analyltes. However, its selectivity toward other breath component needs to be enhanced. Additionally, the integration of nanoparticles in sensors is a key technological development for advancing their performance, miniaturization and decrease in power consumption. Frequently, however, the benefit of nanoscale is lost by poor electrical conductivity through such nanoparticle structures. Thus, it is challenging to achieve both miniaturization with maximized performance and attractive conductivity. Here, a novel asymmetric electrode assembly is described that reduces the resistance of a nanostructured layer and increases its selectivity to acetone. Gold nanoparticles serving as nanoelectrodes are stochastically deposited by flame spray pyrolysis below a functional film decreasing the effective length of the resistive components. The feasibility of this assembly is demonstrated with solid state sensors having controlled resistance and exceptionally high sensitivity to acetone. Au nanoparticles also enable detection of acetone at relatively low temperatures with still high sensor response. Furthermore, the selectivity to acetone was drastically increased.