Performance and Selectivity toward Acetone against Various Gaseous Markers for Liver Diseases of Flame-Made Ir-Loaded In2O3Nanoparticulate Sensors

Abstract

In this work, iridium (Ir) loaded indium oxide (In2O3) nanoparticles made via a flame spray pyrolysis (FSP) technique for the first time were systematically investigated for acetone (C3H6O) detection at ppb levels. The structural data based on microscopic and spectroscopic analyses unveiled that 3–6 nm secondary metallic Ir nanoparticles were loaded on 8–15 nm cubic In2O3nanoparticles with uniform dispersion at a low Ir content of 0.5 wt % or less. Sensing films fabricated from the powders via a spin-coating process were assessed for their gas-sensing properties toward four groups of breath gases including environmental gases, volatile organic compounds, volatile organic acids or short-chain fatty acids, and volatile sulfur compounds. From the test results, the optimum Ir loading level of 0.5 wt % yielded the highest response (S = 6.02–1000 ppb C3H6O) with a low detection limit of 10.7 ppb and good acetone selectivity against numerous breath gases at 300 °C. In addition, the 0.5 wt % Ir-loaded In2O3sensor exhibited a modestly low acetone response decline of less than 25% in humid air (80%RH) at 300 °C. Consequently, the 0.5 wt % Ir-loaded In2O3nanomaterial was attractive for sensitive detections of acetone at ppb levels applicable to medical applications, including initial screening of liver diseases. © 2025 The Authors. Published by American Chemical Society