Metal–metal oxide pH sensors for physiological application

Metal–metal oxide electrodes provide robust and miniaturised pH sensors. Iridium oxide electrodes prepared by thermal oxidation and by anodisation are described and their relative merits discussed. The effects of chloride and protein adsorption on sensor performance are investigated using cyclic voltammetry and the mechanism by which Nafion membranes can stabilise sensor response is identified. Applications in cultured intervertebral disc are reported.