Anti-phase mode isolation in tuning-fork MEMS using a lever coupling design

A new coupling design is proposed and demonstrated for MEMS tuning-fork structures, which successfully isolates the anti-phase vibratory mode in both frequency and Q-factor. G-sensitivity is reduced by design through 1) creation of a high frequency separation between anti-phase and in-phase vibratory modes, 2) maximization of the in-phase resonance frequency, and 3) minimization of in-phase Q-factors. The proposed design accomplishes these goals by using a levering mechanism for coupling the proof masses, in contrast to a conventional approach via flexural spring. This structural design allows for large frequency separations between the anti-phase and in-phase vibratory modes, experimentally demonstrated up to 119% using a previously established quadruple mass gyroscope (QMG) [1]. Furthermore, due to the additional stress present within the lever coupling, in-phase Q-factors are reduced through tailored thermoelastic damping. The result is an anti-phase resonance separated in Q-factor and fQ product by over two orders of magnitude, compared to the in-phase mode. This is shown in comparison to an identical device with a spring coupling, demonstrated with a 25% frequency separation and one order of magnitude separation in both Q-factor and fQ product.