Evaluating Nanomaterials Integrated with Microsensor Arrays for Breath Monitoring
K.D. Benkstein, B. Raman, C.J. Martinez, C.B. Montgomery, S. Semancik
National Institute of Standards and Technology, US
Keywords: nanoparticles, chemical sensors, microsensors
Abstract:We discuss recent efforts in our laboratory to prepare conductometric microsensor arrays using nanostructured sensing films and to evaluate them in simulated exhaled-breath-monitoring experiments. The materials are all metal oxides, and include pure and doped tin(IV) oxides and titanium(IV) oxides with varied morphologies and a sol-gel derived tungsten(VI) oxide film. Our simulated breath studies include a dynamic background, which represents inhalation/exhalation conditions, and varying, relevant concentrations of acetone (0.5 Ámol/mol to 8 Ámol/mol), which is a biomarker for diabetes in exhaled breath. Our analyses (linear discriminant analysis and k-nearest neighbor) indicate that the porous, doped nanoparticle materials (Sb:SnO2 microshell films and Nb:TiO2 nanoparticle films) are best for determining whether acetone is present in exhaled breath, but that undoped films (WO3 and SnO2) are better for differentiating between high and low concentrations of acetone. We conclude with a discussion of methods for tuning these array-based devices to real-time breath monitoring.