Electronic circuit system of high sensitivity mass detection for QCM-biosensor

The paper describes a high sensitivity mass measurement system equipped with an electronic circuit system for biosensors which are used for the detection of dioxins and PCBs, environmental pollutants, and marker proteins for infections. Improvement of the oscillation frequency stability of a QCM is important for the construction of a biosensor with high sensitivity to detect disease viruses, bacteria, dioxins, PCBs, and stress marker proteins. The authors have developed a novel electronic circuit system that can be used to realize a QCM (quartz crystal microbalance) biosensor with highly mass sensitivity at the picogram level. As for design specification, the design technology of the crystal resonator and electronic circuit system for telecommunication equipment was applied. Oscillation frequency of the QCM was 8.93 MHz. A frequency measurement technique employed in telecommunications was used. The oscillation frequency stability for the QCM was 5 ppb/h, and that of the average value was 1 ppm/h. This implies that the mass sensitivity of QCM extended from the nanogram level to the picogram level.