The ME2-CH2O-16×15 formaldehyde sensor is a fuel cell-type electrochemical sensor. Formaldehyde and oxygen undergo corresponding redox reactions on the working electrode and counter electrode, releasing charges and forming an electric current. The magnitude of the generated current is proportional to the concentration of formaldehyde and follows Faraday's law. The concentration of formaldehyde can be determined by measuring the magnitude of the current.