Effect of viscoelasticity on quality factor of microcantilever chemical sensors: optimal coating thickness for minimum limit of detection

Frédéric Lochon (1) , Isabelle Dufour (1) , Dominique Rebiere (1) , Uttara Sampath (2) , Stephen Heinrich (2) , Fabien Josse (2)

1 IMS - Laboratoire de l'intégration, du matériau au système
2 Department of Electrical and Computer Engineering

Microcantilevers with polymer coatings hold great promise as resonant chemical sensors. It is known that the coated cantilever sensitivity increases with coating thickness; however, the drawback of increasing the coating thickness is the increase of the frequency noise and thus the deterioration of the sensor's limit of detection. In this paper, an analytical expression for the viscoelastic losses in the coating, hence the quality factor, is established and is used to explain the observed increase of the frequency noise with the polymer thickness. This result is then used to demonstrate that an optimum coating thickness exists that will minimise the limit of detection.

Domains: Micro and nanotechnologies/Microelectronics

Frédéric Lochon, Isabelle Dufour, Dominique Rebiere, Uttara Sampath, Stephen Heinrich, et al.. Effect of viscoelasticity on quality factor of microcantilever chemical sensors: optimal coating thickness for minimum limit of detection. IEEE Sensors 2005, 2005, Irvine, United States. pp.265-268. ⟨hal-00182217⟩