A novel method for simultaneous impedance analyses of two resonating piezoelectric quartz crystals is proposed via the admittance measurements of two crystals in parallel and then nonlinear admittance fitting to an equivalent circuit of two Butterworth-Van Dyke circuits in parallel. Series of sucrose aqueous solutions and copper electro-deposition/stripping in a NH 3-(NH 4) 2SO 4 buffer were used to test this method, giving that the impedance parameters of each of the parallel crystals reflecting the solution density-viscosity effect or the mass effect were very close to those measured with each single crystal alone. Also, simultaneous impedance measurements at the working and counter electrodes were carried out and discussed.
The quartz crystal microbalance （QCM） was used to monitor the one-day incubation of human breast cancer cells （MCF-7） on the gold electrode. In combination with an optical microscope simulation experiment, the cell-population pictures at various stages, the QCM responses to the cells＇ adhesion, spreading and proliferation on the electrode surface were discussed. The △f0 and △R1 responses were found mainly from mixed effects of viscodensity and surface stress, and in proportion to the cell coverage, rather than to the number of cells at the electrode. The significant fore-and-aft changes in cyclic voltammetry and electrochemical impedance spectroscopy of the ferri-ferrocyanide redox couple also proved that the cells were adhesion to the gold surface.
Xue En JIAZhi Wei ZHANGLiang TANYou Yu ZHANGQing Ji XIEZhi Min HEShou Zhuo YAO
