Design and development of a MEMS-IDT gyroscope

Abstract

The design, development and performance evaluation of a novel radio frequency microelectromechanical systems (MEMS) gyroscope, based on a surface acoustic wave resonator (SAWR) and a surface acoustic wave sensor is presented in this paper. Most of the MEMS gyroscopes based on silicon vibratory structures that utilize the energy transfer between the two vibratory modes demand small fabrication tolerances to minimize signal output when there is no rotation (i.e. zero rate output). This 1 cm × 1 cm gyroscope operates based on the principle of a surface acoustic wave (SAW) on a piezoelectric substrate. The SAWR creates SAW standing waves within the cavity space between the interdigital transducers (IDTs). The particles at the anti-nodes of a standing wave experience large amplitudes of vibration perpendicular to the plane of the substrate, which serves as the reference vibrating motion for this gyroscope. A number of metallic dots (proof masses) are strategically positioned at the anti-node locations so that the effect of the Coriolis force due to rotation will amplify the magnitude of the SAW that is generated in the orthogonal direction. The performance of this 74.2 MHz MEMS-IDT gyroscope has been evaluated using rate table and geophone setups , indicating very high sensitivity and dynamic range, which is ideal for many of the commercial applications. Unlike other MEMS gyroscopes, this gyroscope has a planar configuration with no suspended resonating mechanical structures, thereby being inherently robust and shock resistant. In view of its one-layer planar configuration, this gyroscope can be implemented for applications requiring conformal mounting onto a surface of interest.

A Novel Micro Rate Sensor using a Surface-Acoustic-Wave (SAW) Delay-line Oscillator

“…On the other hand, a SAW-based sensor has not only the superior benefits of inherent shock robustness because of employing no moving mechanical parts but also the simplicity of the fabrication process. Two types of SAWbased gyroscopes, using the standing wave and the propagating wave, have been demonstrated [3][4][5][6]. Though a device using the standing wave showed meaningful performance as a rate sensor, it still had to overcome a substantial temperature drift owing to using a strong piezoelectric coupling material.…”

Gyroscopes based on surface acoustic waves

“…According to their functional principles, SAW gyroscopes are categorized into different types such as standing-wave-mode type gyroscopes, progressive-wave-mode type gyroscopes, and multi-axis detectable SAW gyroscopes, all of which are introduced in this article [10][11][12][13][14][15][16][17][18][19].…”

Development of wireless, batteryfree gyroscope based on one-port SAW delay line and double resonant antenna

“…This type of SAW gyroscope has unique properties such as superior inherent shock and vibration robustness, easy resonance frequency matching between the drive and sense modes, low power consumption, and facile wireless circuit implementation [5][6][7][8]. To date, few research groups have reported on SAW-based gyroscopes that have different designs and structures [9][10][11][12][13][14]. Varadan et al reported a 74.2-MHz MEMS-IDT SAW gyroscope [12], and Kurosawa et al demonstrated the effect of the metal dot array design on the gyroscope's performance [13].…”

“…To date, few research groups have reported on SAW-based gyroscopes that have different designs and structures [9][10][11][12][13][14]. Varadan et al reported a 74.2-MHz MEMS-IDT SAW gyroscope [12], and Kurosawa et al demonstrated the effect of the metal dot array design on the gyroscope's performance [13]. Lee et al presented a micro rate gyroscope, based on the SAW gyroscopic effect on ST quartz that used a differential dual-delay-line oscillator configuration [14].…”