Capacity affinity sensor

Detecting interactions between molecules forms the basis of many analytical methods. The interaction can be detected and quantified through a number of schemes, e.g. precipitation, separation or through different marker molecules or reactions. Such an example is the development of immunoassays during the last three decades, which has revolutionized determination of drugs and hormones in clinical and pharmaceutical chemistry as well as contaminants in the environmental area. Almost all immunomethods require labels attached either to the antibody or the antigen. Another example is the binding between a DNA-probe and its complementary DNA-strand or DNA-fraction. A number of receptors or the complementary molecule can be studied using the same approach. 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.