Sensor response time evaluations of trace hydrogen gaseous species with platinum using Kelvin Probe

Kelvin Probe (KP), a non-contact, non-destructive vibrating capacitor device, was used to measure the work function (WF) difference of thin Pt films, deposited on oxidized silicon substrates, with highly diluted H₂ gas, in ppm levels, in the presence of with and without relative humidity (RH). Response times were extracted from the behavior of WF shift as a function of H₂ concentration values. Measurements were compared for zero and non-zero RH conditions at a fixed temperature of 30°C. Changes in WF were evaluated by using HP VEE program, suitably modified for the present measurements. The events were executed step by step for every second time interval through an input formatted file. The data was recorded at each event and was analyzed for the shift in WF with respect to the H₂ concentration. The shift in the WF and the response time (τ₉₀) at different concentration levels for the Pt films is reported in this paper. The presence of humidity shows saturation of response time after 500 ppm whereas zero humidity conditions show a continuous reduction at higher concentration values.