Response changes of thin film palladium based optical fibre hydrogen sensors over time

Results are presented of a Palladium optical fibre sensor utilising a thin film as the sensing element as a transmission based sensor for the detection of hydrogen. Different thicknesses of Palladium between 8-13nm thick were deposited onto glass slides and tested by repeatedly exposing them to 5% Hydrogen gas in a nitrogen atmosphere. Initially the test samples had response times as low as 4-5 seconds with a change in spectral output up to 15%. Results are presented comparing the initial testing of the palladium slides to tests carried out 6 months later. A change in response for some sensing elements is demonstrated whereas others remain consistent to repeated exposures of Hydrogen gas