First study of humidity sensors based on nanostructured carbon films produced by supersonic cluster beam deposition

We have investigated the feasibility of humidity sensors based on nanostructured carbon (ns-C) films produced by supersonic cluster beam deposition (SCBD). The ns-C films have been obtained using pure He as the buffer gas in the pulsed microplasma cluster source (PMCS). Films of different thickness (1–10 μm) were deposited on Au contacts: resistive- and capacitive-type devices were manufactured. Resistive sensor show a flat response for relative humidity (%RH) up to 60%. Preliminary measurements performed on capacitive-type devices at room temperature in the relative humidity range 10–70% showed a linear dependence of the capacitance on RH%. Fast rise times and a sensitivity of the order of 0.1–0.5 pF/%RH favourably compare with standard commercial sensors and other advanced capacitive devices made with polymers.