Electrical characterization of piezoelectric-on-silicon contour mode resonators fully immersed in liquid

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)216-223
Journal / PublicationSensors and Actuators, A: Physical
Online published15 Feb 2016
Publication statusPublished - 15 Apr 2016


Biological sensing in the mechanical domain offers novel opportunities to measure cellular processes. Operating mechanical resonators in liquid environment for the detection of mass presents a challenge at least for electrical characterization. In this paper, we demonstrate the full electrical characterization of a micromechanical resonator that is fully immersed in DI-water. The reported device uses piezoelectric transduction through an Aluminium Nitride (AlN) film sputtered on a low damping silicon substrate to provide strong electromechanical coupling. The effect of viscous damping in DI-water is lowered by exciting the resonator to vibrate in an in-plane contour mode. We believe that incorporating a 10 µm thicker silicon substrate layer stiffens the resonant system and thereby increases the energy storage capacity in relation to a resonator structured purely by a thin AlN film. The 14 MHz length extensional (LE) mode resonator presented in this paper shows a quality factor (Q) of 200 when fully immersed in DI-water, which is twice that of previously reported resonators structured purely in AlN. The associated motional resistance of the device in DI-water is 40 kΩ. We have also measured the values of Q for several other in-plane resonant modes with higher resonant frequencies (up to 141.69 MHz) when immersed in DI water. Having found that the high dielectric constant of DI-water significant affects the characterization setup, we have also modeled the various sources of parasitics involved in the setup.

Research Area(s)

  • MEMS resonator, Thin film piezoelectric-on-silicon, Feedthrough capacitance, Viscous damping, CANTILEVER SENSORS, CHEMICAL SENSORS, BIOSENSORS, MICROCANTILEVER