Advanced fuel-cell engineering has been employed to breath-alcohol sensors. Devices similar to the Alcosensor fuel cells.

The fuel cell of the Alcosensor has 2 Platinum electrodes and in between these there is a porous acid-electrolyte material. As the breathed out air from the defendant feeds by one side of the fuel cell, the Pt oxidises whatsoever alcohol in the air to create acetic acid, protons and electrons.

The electrons stream by a conducting wire from the Pt electrode. The conducting wire is linked up to an amimeter and to the Pt electrode along the former side. The protons go by the bottom part of the fuel cell and merge with O and the electrons on the different side to build H2O. The more alcohol that gets oxidised, the larger the electrical current. A microprocessor evaluates the electrical current and accounts the BAC.