Novel sensors for potassium, calcium and magnesium ions based on a silicon transducer as a light-addressable potentiometric sensor

Potentiometric cation sensors using a silicon transducer, light-addressable potentiometric sensor (LAPS) and ion-recognition elements are described, and their performance are discussed. In the silicon transducer, an Al2O3 layer was used as an insulating layer. On the surface of the Al2O3 layer, ion-recognition element such as valinomycin, 18-crown-6 ether, bis[di(n-octylphenyl)phosphato]calcium(II) and ETH1117 were immobilized in the matrix of poly(vinyl chloride) film. Potassium tetrakis (p-chlorophenyl)borate was used as a lipophilic salt. The K+, Ca2+ and Mg2+ sensitive-silicon electrodes showed responses similar to those of the corresponding ion-selective electrode. Furthermore, calcium sensing properties of lipophilic anion concentration were studied. It was shown that the presence of lipophilic anion increased the slope. (C) 1999 Elsevier Science B.V. All rights reserved.