ppb-Level ethanol gas sensor of porous anodic aluminum oxide at room temperature

Excessive ethanol in breath can be an indicator of alcoholism and a biomarker of liver disease. Herein, we present a novel porous aluminum anodic oxide (AAO)-based chemi-capacitive sensor that can detect ppb-levels of ethanol gas at room temperature. The oxalic acid-based porous AAO is an amorphous material contaminated with Al(OH)(3) and C2O42- ions (anion-contamination), which react with adsorbed ethanol gas. The optimal resonance frequency of ethanol was determined to be 500 Hz, and the response to 200 ppm ethanol at this frequency was 1.56%. Especially, the limit of detection of ppb-level (16.49 ppb) was obtained. The detection range, reliability, and selectivity of the sensor, as well as its surface properties were comprehensively investigated. The proposed sensor is promising for the detection of liver disease as well as for commercial breath ethanol analyzers.