DOUBLE MATRIX MEMBRANES FOR POTENTIOMETRIC CATION-SELECTIVE DISPOSABLE SENSORS

The construction of double matrix membranes (DMM) for disposable NH4+, Na+ and pH sensors is described. The usual polymer matrix membrane wa s incorporated in an inert micro fibre matrix (MFM). Capillary forces distribute the cocktail homogeneously in the MFM; this also determines the thickness. Sensors using the new DMM have shown selectivity, dete ction limits and slope comparable with polymer matrix membranes. The a dvantages of DMMs are their mechanical stability, the feasibility of l ow cost mass production with identical parameters and improved handlin g.