Wireless gas sensing system enabling real-time seafood freshness monitoring based on Ru-In2O3 microtubes with dual-enhanced sensitivity and selectivity

Abstract

The growing demand for seafood safety necessitates smart sensor with real-time monitoring capability for biomarker, triethylamine (TEA). However, it still faces tremendous challenges due to limited sensitivity and selectivity of sensing material. This study develops a topological transformation from Ru-MIL-68 precursor to Ru-doped In2O3 hollow hexagonal prism. These structural merits, including hierarchical porosity, uniform Ru dispersion, and abundant oxygen vacancies, endow this material with enhanced gas adsorption-diffusion kinetics and surface reactivity. The optimized Ru-In2O3-0.8 sensor exhibits exceptional TEA sensing performance: ultrahigh response (Ra/Rg = 493 ~ 100 ppm), fast recovery (τrec = 22 s), and low detection limit (LOD = 11.3 ppb). Density functional theory calculations delineate that TEA binds preferentially to the Ru-In2O3 surface with a much larger adsorption energy than that of TEA on bare In2O3 or other gas molecules on Ru-In2O3, supporting the enhanced sensitivity and selectivity achieved by introducing Ru. Furthermore, a smart gas sensing system based on Ru-In2O3-0.8 material demonstrates real-time half-fin anchovy freshness monitoring application on mobile phone. This work not only proposes the structure modulations for exploration of advanced sensing materials, but also guides the potential for real-time analysis, monitoring and diagnosis.