Generalized model of resonant polymer-coated microcantilevers in viscous liquid media

Russel Cox (1) , Fabien Josse (1) , Michael Wenzel (1) , Stephen Heinrich (2) , Isabelle Dufour (3)

1 Department of Electrical and Computer Engineering
2 Department of Civil, Construction and Environmental Engineering [Milwaukee]
3 IMS - Laboratoire de l'intégration, du matériau au système

Expressions describing the resonant frequency and quality factor of a dynamically driven, polymer-coated microcantilever in a viscous liquid medium have been obtained. These generalized formulas are used to describe the effects the operational medium and the viscoelastic coating have on the device sensitivity when used in liquidphase chemical sensing applications. Shifts in the resonant frequency are normally assumed proportional to themass of sorbed analyte in the sensing layer. However, the expression for the frequency shift derived in this work indicates that the frequency shift is also dependent on changes in the sensing layer’s loss and storage moduli, changes in the moment of inertia, and changes in the medium of operation’s viscosity and density. Not accounting for these factors will lead to incorrect analyte concentration predictions. The derived expressions are shown to reduce to well-known formulas found in the literature for the case of an uncoated cantilever in a viscous liquid medium and the case of a coated cantilever in air or in a vacuum. The theoretical results presented are then compared to available chemical sensor data in aqueous and viscous solutions.

Domaines: Micro et nanotechnologies/Microélectronique

Russel Cox, Fabien Josse, Michael Wenzel, Stephen Heinrich, Isabelle Dufour. Generalized model of resonant polymer-coated microcantilevers in viscous liquid media. Analytical Chemistry, 2008, 80, pp.5760-5767. ⟨hal-00293888⟩