Journal Article

Fuel cell sensors are electrochemical cells in which a substance is catalytically oxidised giving rise to an electric potential which results in a flow of current in an external circuit. Fuels are commonly readily oxidisable organic substances. formaldehyde being one example and catalysts
are usually highly surface active platinum based types. The detailed mechanism is complex and is not completely understood. but the overall system may be represented simply (in the case of formaldehyde) as
[O>H2O]
2HCHO -> 2HCOOH + 2H+ + 2e
HCHO -> CO2 + 2H+ + 2e-
Fuel cells are extensively used in ethanol (drink driving) monitoring equipment, but can, in theory, be used for any oxidisable species. including inorganic species such as sulphur diozide and carbon monoxide. Most of the current research into fuel cells is not directed towards sensors. but
towards their use as power sources. especially in the automotive industry.