When a film bulk acoustic resonator (FBAR) is coupled to a liquid layer with thickness comparable to the acoustic wavelength, the Q factor varies in a damped oscillatory pattern with the liquid thickness. This letter reports an analytical modeling and experimental demonstration of this behavior by integrating microfluidic channels to MEMS-based FBARs. It is found that Q assumes its maxima and minima when the channel thickness is an odd multiple of quarter-wavelength and a multiple of half-wavelength, respectively. The microfluidics integrated FBARs achieve a 10 × improvement of Q over fully immersed FBARs, showing the potential of use as high-resolution sensors involving liquids.

Original languageEnglish (US)
Article number5742672
Pages (from-to)2342-2343
Number of pages2
JournalIEEE Sensors Journal
Issue number10
Publication statusPublished - 2011



  • Acoustic resonators
  • microfluidic channel
  • piezoelectric transducers
  • Q-factor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Instrumentation

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