Buehler, M., Kuhlman, G., Myung, N., Keymeulen, D. et al., "Planar Array REDOX Cells and pH Sensors for ISS Water Quality and Microbe Detection," SAE Technical Paper 2003-01-2553, 2003, doi:10.4271/2003-01-2553.
This paper describes results acquired from E-Tongue 2 and E-Tongue 3 which are arrays of planar three-element electrochemical cells and pH sensors. The approach uses ASV (Anodic Stripping Voltammery) to achieve a detection limit, which in the case of Pb, is below one μM which is needed for water quality measurements. The richness of the detectable species is illustrated with Fe where seven species are identified using the Pourbiax diagram. The detection of multiple species is illustrated using Pb and Cu. The apparatus was used to detect the electroactivity of the metabolic-surrogate, PMS (phenazine-methosulphate). Finally, four types of pH sensors were fabricated and characterized for linearity, sensitivity, and responsiveness.