Development of an integrated in-vehicle driver breath ethanol system based on α-Fe₂O₃ sensing material

Advanced Driver Assistance Systems are intelligent systems located inside vehicles to assist the main driver in a variety of ways. These systems may be used to provide useful traffic information, but may also be used to evaluate whether or not the driver is in physical conditions to drive.

Among other driver-related risk factors (e.g. drug intake or altered emotional state), alcohol abuse remains the dominant cause of fatal car accidents (about 25% of all road deaths in Europe).

For this reason, our research activity is aimed at the realization of an in-vehicle driver breath ethanol detection system.

To facilitate the large-scale implementation of these systems, the design of inexpensive, reliable and easy to prepare sensors is required. Iron oxide possesses all these characteristics, and it has been shown to have a remarkable sensing capacity for ethanol. For these reasons, it is an ideal candidate as a material to be used for alcohol level monitoring in ADAS systems.

In this work, a simple Pechini sol-gel process was used to prepare a stable water solution used to print a thin film on ceramic sensor substrates. The α-Fe₂O₃ thin film-based sensor obtained exhibits a highly selective sensing behaviour towards ethanol and a very stable response in time.

The Fe₂O₃-based material has been employed in a breath ethanol detection system experimental setup given the promising preliminary results.

Tests were performed by placing the ethanol sensor within the casing of a car upper steering column, for simulating driving position.

The main challenge in the development of this system is related to the complexity of breath composition and its high humidity content, coupled with the high dilution of breath reaching the sensor.

For this reason, it was necessary to install the ethanol sensor into an array that also contains humidity and CO2 sensors (the latter, a compact ND-IR sensor was employed as an internal standard).

Finally, through the simultaneous use of these three sensors, it was possible to differentiate the signal of a driver's breath before and after alcohol consumption.