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Direct comparison of the gravimetric responsivities of ZnO-based FBARs and SMRs

García-Gancedo, L and Pedrós, J and Iborra, E and Clement, M and Zhao, XB and Olivares, J and Capilla, J and Luo, JK and Lu, JR and Milne, WI and Flewitt, AJ (2013) Direct comparison of the gravimetric responsivities of ZnO-based FBARs and SMRs. Sensors and Actuators, B: Chemical, 183. pp. 136-143. ISSN 0925-4005

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Abstract

Film bulk acoustic resonators (FBARs) and solidly mounted resonators (SMRs) have the potential to significantly improve upon the sensitivity and minimum detection limit of traditional gravimetric sensors based on quartz crystal microbalances (QCMs) and surface acoustic wave resonators (SAWs). To date, neither FBAR nor SMR devices have been demonstrated to be superior to the other; hence the choice between them depends primarily on the users' ability to design/fabricate membranes and/or Bragg reflectors. In this work, it is shown that identically designed FBAR and SMR devices resonating at the same frequency exhibit different responsivities to mass loadings, Rm, and that the SMRs are less responsive than the FBARs. For the specific device design and resonant frequency (~2 GHz) of the resonators presented here, the FBARs' mass responsivity is ~20% greater than that of the SMRs', and although this value is not universal for all possible device designs, it clearly shows that FBAR devices should be favoured over SMRs in gravimetric sensing applications where the FBARs' fragility is not an issue. Numerical calculations based on Mason's model offer an insight into the physical mechanisms behind the greater FBARs responsivity, and it was shown that the Bragg reflector has an effect on the acoustic load at one of the facets of the piezoelectric films which is in turn responsible for the SMRs' lower responsivity to mass loadings. © 2013 Elsevier B.V.

Item Type: Article
Uncontrolled Keywords: BAW resonators Gravimetric biosensor Piezoelectric biosensor Zinc oxide (ZnO)
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:28
Last Modified: 08 Dec 2014 02:19
DOI: 10.1016/j.snb.2013.03.085