Self-Magnetic Excitation for In-Plane Mode Resonant Microsensor

A novel self-magnetic excitation mechanism for resonant microsensors vibrating in a rotational in-plane mode is presented. The excitation scheme is based on magnetic forces acting between two current carrying conductors and requires no external magnetic field. In combination with piezoresistive detection elements, the magnetic driving scheme has been applied to disk-shape microresonators. With 10 mA current, a net torque of approx. 10^-13N · m is extracted from finite element simulations. Paired with the relatively large Q-factor of the in-plane resonators, this torque is sufficient to drive the resonator in a closed-loop configuration. Resonant microsensors with different dimensions have been fabricated and characterized in air, achieving quality factors up to 4800 and short-term frequency stabilities better than 5.5 × 10^-8using the Allan-variance method.