We have developed a high-sensitivity, high-precision quartz crystal microbalance (QCM) immunosensor system (QCM system) with a flow cell. The stability of the oscillating frequency of QCM in a solution was a serious problem with conventional QCM systems. We successfully improved the stability by more than one order of magnitude by decreasing the phase noise: this resulted in a highly-sensitive, highly precise and rapid measurement of an immunoreaction.

This QCM system allows us to detect the presence of a target substance with high selectivity. A substance (antibody or antigen) that binds specifically to the target substance (antigen or antibody respectively) is immobilized on the gold electrode surface of the QCM-sensor. When the antibody binds to the antigen, there occurs a detectable change in the oscillating frequency of the QCM-sensor device. We expect this QCM-system to be useful in highly sensitive, very precise analyses of substance such as dioxins, endocrine disruptors, pesticide residues, allergens, stress markers, disease markers, and pathogenic microbes.