Solid-state sensors monitoring parameters of water quality for the next generation of wireless sensor networks

In this review solid-state sensors for on-line monitoring of such water quality parameters as pH, dissolved oxygen (DO), conductivity, turbidity, dissolved organic carbon (DOC) and dissolved metal ions on the high spatial resolution were analysed. It has been established that the next generation of wireless sensor networks can be successfully coupled with accurate, inexpensive, robust and miniature solid-state sensors based on thin- or thick-film semiconductor sensing electrode (SE), which can overcome bio-fouling difficulties. In the development of highly sensitive and selective nanostructured SEs, the control of their structures and morphologies plays an increasing importance as a critical factor determining their properties. Even for nano-scaled complex oxide SEs structural factor remains a complicated concept. Doping semiconductor SE by another nano-oxide has been proven to be a very effective way to modernise suitable properties of the SE toward better selectivity and higher antifouling resistance. Results, mainly obtained during studies of the doped complex oxide SEs of the various chemical sensors have been used for showing the optimisation of the sensors’ characteristics. Examples of the different sensors and their improved characteristics have been discussed.