Sensors Based on Tin and Indium Oxides for the Determination of Acetone in Human Breath

The properties of planar sensors based on tin dioxide and indium oxide used for the determination of acetone vapors have been studied. Sensors based on synthesized SnO₂ and In₂O₃ nanopowders showed high sensitivity to low concentrations of acetone in a humid environment which simulates human exhalation. The addition of a small amount of Au^III ions to hydroxide sols significantly increases the threshold sensitivity and the sensor response in a wide range of acetone concentrations. In₂O₃-Au sensors have the maximum sensitivity at an operating temperature of 325 °C. The In₂O₃-Au-sensors reliably record the change in acetone concentration in the concentration range from a minimum of 0.1 to 5 ppm with high accuracy, which is necessary for rapid diagnostics of the condition of patients with diabetes (1.8-5.0 ppm). The high sensitivity of the obtained sensors is explained by the structural features and the surface conditions of oxides and gold nanoparticles, which depend on the sample synthesis conditions.