Patent ID: 7972864

Claim:
A method of measuring concentration of a fuel, comprising: providing a fuel cell unit comprising at least an anode, a cathode, and a membrane electrode assembly (MEA); establishing at least one open circuit voltage vs, time curve corresponding to at least one known concentration of a fuel, wherein the method of establishing the at least one open circuit voltage vs, time curve comprises: (a) supplying the fuel having one known concentration to the anode; (b) supplying a reactive gas to the cathode; (c) stopping supplying the reactive gas to the cathode and measuring open circuit voltage of the MEA so as to obtain one open circuit voltage vs, time curve thus considerably reducing a measurement time; (a)′ supplying the fuel having an unknown concentration to the anode; (b)′ supplying the reactive gas to the cathode; (c)′ stopping supplying the reactive gas to the cathode and measuring open circuit voltage of the MEA so as to obtain a new open circuit voltage vs, time curve; and comparing the new open circuit voltage vs, time curve with the at least one open circuit voltage vs, time curve, so to estimate the concentration of the fuel having the unknown concentration.