Toward A Levitated Micromechanical Resonator


Capacitive micromechanical (MEMS) resonators promise to dramatically improve the design of RF frontends for wireless communications by virtue of their high quality factor (Q). Unfortunately, the physical limitations of MEMS resonators’ are poorly understood, and the highest Qs have proven difficult to achieve reliably. In order to further development of reliably highresonators, a levitated resonator is proposed. This device aims to eliminate anchor loss, which affects the quality factor of resonators in vacuum conditions. By removing the anchors, the intrinsic of the material can be measured, as determined by material, surface, and other losses.

A spherical geometry is chosen, and its resonant modes are analyzed. Three modes are considered to be of interest: the firstand secondorder radial modes, and the firstorder ellipsoidal mode. The mode shapes, resonance frequencies, and equivalent masses of all three modes are calculated using analytical formulas and verified using finiteelement analysis.

A prototype fabrication process is developed and carried out, using offtheshelf metal spheres for the resonator and commercial printed circuit boards (PCBs)for the electrode structures. This process can produce resonators with radii down to 150 μm or less. An alternative, waferbased fabrication process is proposed for future work with smaller device dimensions.

An electrostatic levitation mechanism is proposed. Dynamically stabilized electrostatic levitation is found to be possible with voltages less than 100 V. The levitated resonator requires sensitive electronics to excite and detect its resonance, as well as to stabilize it under applied electrostatic fields. A preliminary design of these electronics is carried out.

Publication date: 
May 31, 2010
Publication type: 
Master's Thesis
Gurin, I. (2010). Toward a Levitated Micromechanical Resonator. United States: University of California, Berkeley.

*Only registered BSAC Industrial Members may view project materials & publications. Click here to request member-only access.