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SUMMARY:The Engineering of Thin Film Bulk Acoustic Resonator Gravimetric S
 ensors - Dr Andrew Flewitt (University of Cambridge)
DTSTART:20180215T113000Z
DTEND:20180215T123000Z
UID:TALK101467@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Thin Film Bulk Acoustic Resonators (TFBARs) are currently wide
 ly employed as communications filters\, duplexers and multiplexers in mobi
 le telephones.  They consist of a thin film of a piezoelectric material on
  the surface of a silicon wafer with electrodes above and below the thin f
 ilm which are designed to overlap in a small area (~100 × 100 µm).  By a
 pplying an a.c. electrical signal to the electrodes\, an oscillating mecha
 nical deformation can be set up in the piezoelectric material to produce a
 n acoustic wave.  When the half wavelength matches the thickness of the pi
 ezoelectric film\, a standing wave resonance is produced\, typically at a 
 frequency ~1 GHz.  In order to achieve a high Q-factor\, the acoustic ener
 gy must be confined in the resonant area\, and this is achieved either by 
 removing the silicon substrate underneath the resonant area to create a Fi
 lm Bulk Acoustic Resonator (FBAR)\, or by using an acoustic Bragg reflecto
 r of multiple layers of high and low acoustic impedance materials between 
 the resonator and the silicon substrate to create a solidly mounted resona
 tor (SMR).\n\nIn addition to their use in mobile communications\, the TFBA
 R can be used as a gravimetric sensor.  Although the thickness of the piez
 oelectric thin film has primary control of the resonant frequency of the T
 FBAR\, it is also sensitive to mass on the surface of the electrodes.  By 
 functionalising the surface of the TFBAR in a specific chemical or biologi
 cal receptor\, it is possible to detect particular chemical or biological 
 species.\n
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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