Title :
Using quartz crystal microbalances to simultaneously sense mass accumulation and solution properties
Author :
Martin, S.J. ; Granstaff, V.E. ; Frye, G.C. ; Ricco, A.J.
Author_Institution :
Sandia Nat. Lab., Albuquerque, NM, USA
Abstract :
A lumped-element equivalent circuit model is presented that describes the near-resonance electrical characteristics of a quartz crystal microbalance (QCM) simultaneously loaded by a surface mass layer and a contacting liquid. The model was derived by solving the boundary-value problem for coupled mechanical displacement and electrical potential; this results in circuit elements that are explicitly related to physical properties of the quartz, the perturbing mass layer, and the contacting liquid. The effects of mass and/or liquid loading on the admittance-vs.-frequency behavior are predicted from the model and compared with experimental impedance analyzer measurements. Surface mass accumulation causes a simple translation in frequency of the resonance peak, while increasing the density-viscosity product of the contacting solution causes both a translation and a damping of the resonance peak. Using the model, changes in surface mass can be differentiated from changes in solution properties.<>
Keywords :
balances; boundary-value problems; crystal resonators; electric sensing devices; equivalent circuits; micromechanical devices; SiO/sub 2/; admittance; boundary-value problem; contacting liquid; damping; density-viscosity product; electrical potential; liquid phase chemical sensors; lumped-element equivalent circuit model; mass accumulation; mechanical displacement; near-resonance electrical characteristics; quartz crystal microbalances; resonance peak; simultaneously loaded; solution properties; surface mass layer; Contacts; Coupling circuits; Electric potential; Electric variables; Equivalent circuits; Impedance measurement; Mechanical factors; Predictive models; Resonance; Surface impedance;
Conference_Titel :
Solid-State Sensors and Actuators, 1991. Digest of Technical Papers, TRANSDUCERS '91., 1991 International Conference on
Conference_Location :
San Francisco, CA, USA
Print_ISBN :
0-87942-585-7
DOI :
10.1109/SENSOR.1991.149000
