Biosensor Using a Quartz-crystal Microbalance

A piezoelelctric quartz-crystal plate can be used as a microbalance (a quartz-crystal microbalance, QCM). When substances adsorbed on a gold electrode, a fundamental frequency of a QCM is decreased linearly with increasing mass on the electrode. The host molecule-immobilized QCM is used as a biosensor responding to the addition of guest molecules in aqueous solution in nanogram level.