Hydrogen sensing process

A method of measuring a hydrogen concentration in a gas, the method comprising:

• exposing a hydrogen sensor to the gas, the hydrogen sensor comprising a pump cell, a measuring cell, and an insulating layer interposed between the pump cell and the measuring cell, wherein the pump cell comprises a first pump electrode exposed to the gas, a second pump electrode in operable communication with a diffusion-limiting barrier, and a first conducting electrolyte interposed between the first and second pump electrodes, wherein the measuring cell comprises a sensing electrode in operable communication with the diffusion-limiting barrier, a reference electrode in fluid communication with a reference gas source and a second conducting electrolyte interposed between the sensing and the reference electrodes, and wherein the diffusion limiting barrier has a pore size sufficient to produce a Knudsen diffusion mechanism at hydrogen concentrations greater than about 40%;
• applying a voltage to the first and the second pump electrodes to form a pump current;
• diffusing hydrogen molecules across the diffusion-limiting barrier;
• generating an electromotive force signal between the sensing electrode and the reference electrode;
• and
• adjusting the pump current to maintain the electromotive force signal at a predetermined value, wherein the hydrogen concentration is proportional to the pumping current.