CORRECTION FOR THE EFFECTS OF VISCOELASTIC CHANGES IN A PIEZOELECTRICQUARTZ-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 t he frequency can be corrected by the proposed multiple linear regressi on (MLR) method, which is applied to relate frequency shifts with the resonant admittance (or resistance) and mass changes. The regression e quation can be used to correct for the effects caused by the viscoelas tic changes. It has been found that the MLR method using resonant resi stance as a variable is more effective for less viscoelastic films whi le the MLR method using resonant admittance as a variable is more effe ctive for more viscoelastic films. Electrochemical synthesis of polyan iline in perchloric acid solutions was used successfully as a model to test the validity of the method.