title: 170-MHz electrodeless quartz crystal microbalance biosensor: capability and limitation of higher frequency measurement.
abstract: We develop a highly sensitive quartz crystal microbalance (QCM) biosensor with a fundamental resonance frequency of 170 MHz. A naked AT-cut quartz plate of 9.7 microm thick is set in a sensor cell. Its shear vibration is excited by the line wire, and the vibration signals are detected by the other line wire, achieving the noncontacting measurement of the resonance frequency. The mass sensitivity of the 170 MHz QCM biosensor is 15 pg/(cm2 Hz), which is better than that of a conventional 5 MHz QCM by 3 orders of magnitude. Its high sensitivity is confirmed by detecting human immunoglobulin G (hIgG) via Staphylococcus protein A immobilized nonspecifically on both surfaces of the quartz plate. The detection limit is 0.5 pM. Limitation of the high-frequency QCM measurement is then theoretically discussed with a continuum mechanics model for a plate with point masses connected by elastic springs. The result indicates that a QCM measurement will break down at frequencies one-order-of-magnitude higher than the local resonance frequency at specific binding cites.
authors.affiliation: Graduate School of Engineering Science, Osaka University, Machikaneyama 1-3, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ogi
authors.forename: Hironao
authors.initials: H
authors.lastname: Nagai
authors.forename: Hironao
authors.initials: H
authors.lastname: Naga
authors.forename: Yuji
authors.initials: Y
authors.lastname: Fukunishi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hirao
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nishiyama
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D011791:Quartz / Q000737:chemistry*; D013205:Staphylococcal Protein A / Q000276:immunology / Q000378:metabolism
chemical_list: D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D011791:Quartz