Ring-Shaped Silicon Resonator Using (2,1) In-Plane Resonance Mode

Abstract

A ring-shaped low-frequency resonator operating in the in-plane (2,1) mode was designed and fabricated utilizing anodic bonding of a 9-µm-thick single-crystal silicon to a glass substrate. Although the gap between the ring and the driving electrode was relatively large (900 nm), a high quality factor of 4212 at 1.609 MHz was realized. The motional resistance was 1.853 MW. In addition, the resonant frequency was electrically tuned by varying the dc bias of drive electrodes with 21.5 ppm/V. Therefore, it was expected that this resonator could possibly replace low frequency quarts resonators of a few MHz ranges.

Precise extension-mode resonant sensor with uniform and repeatable sensitivity for detection of ppm-level ammonia

“…As is schematically shown in figure 2(a), we employ a dog-bone shaped resonator with both resonance exciting and signal reading elements integrated for on-the-spot gas sensing. Operated in longitudinal extension resonance mode, the recently developed 'dog-bone' resonating structures are mainly utilized as telecommunication devices for timing and frequency reference [23][24][25]. Herein, the structure is modified with a couple of molecule-adsorbing plates that mechanically link the stretching/compressing resonant arms.…”

“…Our analysis, which will be detailed in a following section, shows that one major reason causing the inaccuracy originates from the non-uniform resonating amplitude at different sensing locations. To configure a uniform-amplitude resonating structure that is able to achieve precise and reproducible sensitivity, we herein propose to employ a dogbone shaped resonant micro-sensor that vibrates in an inplane extensional bulk mode instead of the previous outof-plane modes [23][24][25]. This sensor possesses a couple of sensing plates that feature uniform-amplitude vibration, thereby achieving a linear and reproducible response to gas.…”