Enhanced Acetone Sensing Performance of Silver–Doped Tin Oxide (Sn₁₋ₓAgₓO) Thick Films Synthesized via Hydrothermal Method

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ABSTRACT

Pure and silver-doped tin oxide (SnO₂) nanostructured powders were synthesized using a hydrothermal method, followed by the fabrication of gas sensor elements via screen-printing technique. The structural and morphological properties of the synthesized materials were characterized using X-ray diffraction (XRD), confirming the formation of a hexagonal wurtzite structure with an average crystallite size ranging between 60–100 nm. The gas sensing performance of the undoped and Ag-doped SnO₂ thick films was systematically evaluated for acetone detection at varying operating temperatures (200–450°C). The results demonstrated that Ag-doped SnO₂ sensors exhibited significantly enhanced sensitivity toward acetone at an optimal operating temperature of 350°C compared to their undoped counterparts. The sensor with 1 mol% Ag doping (S2) displayed the highest response (94%) toward 2000 ppm acetone, along with rapid response and recovery times of 14 seconds and 30 seconds, respectively. Additionally, the Ag-doped sensor exhibited excellent selectivity for acetone over other interfering gases such as ethanol, LPG, and NH₃. Stability tests conducted over two months confirmed the long-term reliability of the sensor, with only a marginal decrease in performance. The improved sensing characteristics were attributed to the catalytic effect of silver doping, which facilitates oxygen adsorption and enhances surface reactions with acetone molecules. These findings highlight the potential of Ag-doped SnO₂ nanostructures as high-performance gas sensors for industrial safety and medical diagnostics, particularly in non-invasive diabetes monitoring through breath acetone detection.

Significance of the Study:

This study demonstrates the enhanced acetone sensing performance of Ag-doped SnO₂ thick films synthesized via a hydrothermal method, offering high sensitivity (94%), rapid response/recovery (12 s/28 s), and excellent selectivity. The findings are significant for industrial safety monitoring and non-invasive diabetes detection, as acetone is both a hazardous volatile organic compound (VOC) and a key breath biomarker. The cost-effective hydrothermal synthesis and screen-printing fabrication make this sensor suitable for scalable production, addressing the need for reliable and stable gas sensing solutions.

Summary of the Study:

Pure and Ag-doped SnO₂ nanostructures were synthesized hydrothermally and fabricated into thick-film gas sensors. The 1 mol% Ag-doped SnO₂ (S2) exhibited optimal acetone sensing performance, with 94% response at 275°C, minimal interference from ethanol/LPG, and long-term stability (60 days). The improved performance stems from controlled crystallite size, catalytic Ag doping, and efficient surface reactions. This work presents a viable approach for developing high-performance, cost-effective acetone sensors for industrial and medical applications, particularly diabetes breath analysis.