Abstract: A method for measuring hydrogen concentration in a gas includes exposing a PdNi alloy thin-film gas sensor to the gas, alternately controlling the temperature of the PdNi alloy thin-film gas sensor between a first temperature for a first period of time and a second temperature for a second period of time while the PdNi alloy thin-film sensor is exposed to the gas, continuously monitoring the resistance of the PdNi alloy thin-film gas sensor during the first and second periods of time, and calculating the hydrogen concentration as a function of a transient in the resistance of the PdNi alloy thin-film sensor measured at a time that the temperature transitions between the first temperature and the second temperature.

Abstract: A method for measuring hydrogen concentration in a gas includes exposing a PdNi alloy thin-film gas sensor to the gas, alternately controlling the temperature of the PdNi alloy thin-film gas sensor between a first temperature for a first period of time and a second temperature for a second period of time while the PdNi alloy thin-film sensor is exposed to the gas, continuously monitoring the resistance of the PdNi alloy thin-film gas sensor during the first and second periods of time, and calculating the hydrogen concentration as a function of a transient in the resistance of the PdNi alloy thin-film sensor measured at a time that the temperature transitions between the first temperature and the second temperature.

Abstract: A protective coating sustains the long term performance of a solid-state hydrogen sensor that includes a catalyst layer for promoting the electrochemical dissociation of hydrogen. The catalyst is susceptible to deterioration in the presence of at least one contaminant, including carbon monoxide, hydrogen sulfide, chlorine, water and oxygen. The coating comprises at least one layer of silicon dioxide having a thickness that permits hydrogen to diffuse to the catalyst layer and that inhibits contaminant(s) from diffusing to the catalyst layer. The preferred coating further comprises at least one layer of a hydrophobic composition, preferably polytetrafluoroethylene, for inhibiting diffusion of water through the protective coating to the catalyst layer. The preferred protective coating further comprising at least one layer of alumina for inhibiting diffusion of oxygen through the protective coating to said catalyst layer.