Correction for the effects of viscoelastic changes in a piezoelectric quartz crystal by the multiple linear regression method

Resonant frequency and resonant admittance are recorded in situ for a piezoelectric quartz crystal. The effects of viscoelastic changes on the frequency can be corrected by the proposed multiple linear regression (MLR) method, which is applied to relate frequency shifts with the resonant admittance (or resistance) and mass changes. The regression equation can be used to correct for the effects caused by the viscoelastic changes. It has been found that the MLR method using resonant resistance as a variable is more effective for less viscoelastic films while the MLR method using resonant admittance as a variable is more effective for more viscoelastic films. Electrochemical synthesis of polyaniline in perchloric acid solutions was used successfully as a model to test the validity of the method.