Analysis of breath alcohol with a multisensor array: instrumental setup, characterization and evaluation

Abstract

The purpose of this work was to evaluate if it was possible to measure the alcohol concentration in breath by a multisensor array, i.e. an electronic nose. The most important aspects were to clarify technical advantages and disadvantages and if the technique is at all suitable for forensic breath alcohol analysis. Even though the system set-up was far from optimal it is clear that it was possible to quantify breath alcohol with a best-case root mean square error=16.8 mol ppm ethanol (=0.037 mg/l). However, the method needs significant development especially of the sensor devices. The sensor array was composed of ten metal oxide silicon field effect transistors (MOSFET) with various catalytic gates and one infrared-based CO 2 sensor. The system was evaluated by monitoring the breath ethanol concentration of five test persons after intake of alcohol. Gas chromatography was used in parallel to measure the actual breath alcohol concentration. Different data evaluation techniques applied were projection to latent structure (PLS) and artificial neural networks (ANN).