Au-Decorated Sn₃O₄ Nanoflower-Based MEMS Gas Sensor for Detecting ppb-Level Acetone

This paper reports the synthesis and gas sensing performance of Au-decorated Sn 3 O 4 (Au/Sn 3 O 4 ) nanoflowers as gas-sensitive materials for acetone gas sensors. Sn 3 O 4 nanoflowers were first synthesized via a hydrothermal reaction and then were decorated with Au nanoparticles by reducing the Au ions in HAuCl 4 . The phase structure, surface morphology, specific surface area, and surface chemical composition of the synthesized samples were systematically investigated. The morphological characterization confirmed the flower-like structures of Au/Sn 3 O 4 samples, which were composed of Sn 3 O 4 nanosheets and uniformly dispersed Au nanoparticles. The synthesized Sn 3 O 4 and Au/Sn 3 O 4 nanoflowers were applied as gas-sensitive materials in low-cost integrated microelectro-mechanical system-based acetone sensors. Among these, the Au/Sn 3 O 4 sensors demonstrated superior performance, with a higher response ( R air / R gas = 6.1) and faster response/recovery time (9 s/25 s) toward 5 ppm acetone gas at a low operating temperature of 160 °C compared to the Sn 3 O 4 sensors. In addition, Au/Sn 3 O 4 sensors also presented high selectivity to acetone gas under complex atmospheric conditions, with an extremely low detection limit of 50 ppb. The results suggest that the designed acetone gas sensors are expected for early screening and diagnosis of diabetes through monitoring the acetone gas in exhaled breath.