Sputtered thin films of CuBr as electrochemical microsensors for NH3 gas: structure, sensitivity and aging effects

Sputtered films of CuBr with inter-digitated copper electrodes are used as electrochemical detectors for NH3 gas. The current–voltage characteristics are ohmic and depend on the NH3 partial pressure, P, with a fast response. The quantitative relation between the resistivity change Δρ and P is described by a Langmuir-type adsorption isotherm with an adsorption constant K=12 mbar−1. The square-root time dependence of ρ is consistent with a diffusion-limited aging mechanism.