Abstract: This invention relates to a metal ion specific capacitance sensor with exceptional sensitivity and wide operating range. It is versatile because different kinds of recognition elements can be immobilized directly in a self-assembling monolayer substantially completely covering the surface of the measuring noble metal electrode. The electrode then becomes selective to those metal ions in the solution that show affinity to the recognition element on the surface. Compared to previously described electrochemical sensors, the sensor according to the present invention shows many orders of magnitude better sensitivity because of the unique measuring principle.

Abstract: This invention describes a capacity affinity sensor based on self-assembled monolayers on an electrode with immobilized recognition elements available to analyte in the surrounding solution. Additional insulation is provided by auxiliary self-assembled molecules. The sensor has exceptional sensitivity and wide operating range due to these parts of the invention. It is versatile because different kinds of recognition elements can be immobilized directly on the surface of the measuring electrode. The electrode then becomes selective to those molecules in the solution, the analytes, that show affinity to the recognition element on the surface. Compared to capacitive sensors described before those described here shows at least a 1000-fold better sensitivity because of the properties of the layer binding the recognition element.

Abstract: An electrode preferentially sensitive to the activity of zinc ions Zn.sup.+2 in solution. A liquid organic phase containing an appropriate liquid ion exchanger and solvent is combined with means for containing the liquid organic phase as an interface between the organic phase and the solution. Electrical contact with the liquid organic phase at a fixed potential is provided. Zinc ion activity is measured using a standard calomel electrode as a reference, from which the zinc ion concentration is determined.