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TitleMeasurement of the equivalent circuit parameters of chemical interface layers on bulk acoustic wave resonators
Publication TypeConference Paper
Year of Publication2005
AuthorsGouws, G.J., Holt R.C., and Zhen J.
Conference NameProceedings of the IEEE International Frequency Control Symposium and Exposition
Date Published2005
KeywordsAcoustic bulk wave devices, Acoustic waves, Cavity resonators, Complex shear modulus, Electric impedance, Frequency shift keying, Impedance measurement, Networks (circuits), PDMS, Polydimethylsiloxane (PDMS), Polyethylene oxides, TSM resonators, Viscoelastic films, Viscoelasticity
AbstractThe viscoelastic properties of thin polymer layers coated on a thickness shear mode (TSM) resonator is investigated by analysis of the impedance spectra of the resonator. The response of resonators coated with polyethyleneoxide (PEO) and polydimethylsiloxane (PDMS) to organic vapours is described. The PEO coated sensor shows the conventional Sauerbrey behaviour of a negative frequency shift with adsorbed mass, but the PDMS coated sensors show a strong positive frequency shift. The complex shear modulus for these layers is calculated and it is found that the PDMS is in the rubbery state. The in-diffusion of organic vapours leads to a further softening of the layer which produces the positive frequency shift. ©2004 IEEE.

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