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Jan Weber
Investigation of the Physical Properties, Performance and Application of MEMS Sensors Based on Bulk Acoustic Waves excited in Piezoelectric Thin Film Devices
Supervisor: Prof. Dr. Achim Wixforth [Experimental physics I]
Date of oral examination: 05/16/2007
162 pages, english
In this work, piezoelectric thin film resonators (FBARs) are investigated and their performance and aptitude in different sensing applications is evaluated. The theoretic and experimental analysis of the acoustic mode structure yielded important results describing the nature of different modes and providing information for resonator optimization. With an appropriate design a significant im-provement of the sensitivity and quality factor can be achieved. Different modes can be furthermore exploited to enhance the functionality of the sensor and a selection of specific modes by applying a structure on top of the resonator seems possible. Furthermore the influence of design parameters such as the operation frequency, resonator size, form and electrode thickness on the device perform-ance were investigated in detail. Different sensing applications were tested from a stress- over a viscosity- to a bio-sensor and also the capability to act as a fluid mixer was tried successfully. The performance in all these applications was evaluated experimentally and backed up with theoretical models. In comparison experiments acting as a biosensor the FBAR was found to be slightly better than the established quartz crystal microbalance.