Stacking growth of ionically conductive MOF on biofabrics enables reliable NH3 sensor for hepatic encephalopathy diagnosis

Abstract

Aiming at the poor selectivity of electrically conductive metal-organic framework (EC-MOF) chemoresistive materials, this study develops a breakthrough room temperature ammonia (NH₃) sensor by stacking ionically conductive MOF (IC-MOF) on an environmentally friendly biofabric. The synergism between ionic conductivity, tailored metal-nitrogen interaction, and fabric porosity enables the sensor with high response (R₀/R_g = 14.7 towards 1 ppm NH₃), low detection limit (36 ppb), and remarkable selectivity (coefficient >5.12 against common organic interferents). Notably, the optimized sensor yields a sixfold enhancement in response as compared with traditional EC-MOF powders. A linear regression model validated by fivefold cross-validation achieves 98.4% accuracy in NH₃ concentration prediction, while the kNN classifier shows 96% accuracy in gas identification (tested on 192 samples). Preliminary clinical tests show that the sensor can clearly differentiate the exhaled NH₃ signals of four patients with HE from those of healthy individuals, demonstrating the potential for non-invasive diagnostics.