Applied Mathematics and Mechanics (English Edition) ›› 2011, Vol. 32 ›› Issue (6): 749-756.doi: https://doi.org/10.1007/s10483-011-1454-9

• Articles • Previous Articles     Next Articles

Active control scheme for improving mass resolution of film bulk acoustic resonators

HE Xue-Feng1, LIU Xin1, YIN Xian-Fang2, WEN Zhi-Yu2, CHEN Ke-Wan1   

  1. 1. Key Laboratory of Optoelectronic Technology and Systems of Ministry of Education of China, Chongqing University, Chongqing 400044, P. R. China;
    2. Microsystem Research Center, Chongqing University, Chongqing 400044, P. R. China
  • Received:2011-03-23 Revised:2011-04-04 Online:2011-06-01 Published:2011-06-01
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 61076106), the National High Technology Research and Development Program of China (863 Program) (No. 2008AA04Z310), and the Cultivation Fund of the Key Scientific and Technical Innovation Project of Ministry of Education of China (No. 708072)

Abstract: High mass resolution of sensors based on film bulk acoustic resonators (FBARs) is required for the detection of small molecules with the low concentration. An active control scheme is presented to improve the mass resolution of the FBAR sensors by adding a feedback voltage onto the driving voltage between two electrodes of the FBAR sensors. The feedback voltage is obtained by giving a constant gain and a constant phase shift to the current on the electrodes of the FBAR sensors. The acoustic energy produced by the feedback voltage partly compensates the acoustic energy loss due to the material damping and the acoustic scattering, and thus improves the quality factor and the mass resolution of the FBAR sensors. An explicit expression relating to the impedance and the frequency for an FBAR sensor with the active control is derived based on the continuum theory by neglecting the influence of the electrodes. Numerical simulations show that the impedance of the FBAR sensor strongly depends on the gain and the phase shift of the feedback voltage, and the mass resolution of the FBAR sensor can greatly be improved when the appropriate gain and the phase shift of the feedback voltage are used. The active control scheme also provides an effective solution to improve the resolution of the quartz crystal microbalance (QCM).

Key words: film bulk acoustic resonator, sensor, active control, impedance, resolution

2010 MSC Number: 

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