A multi-functional MEMS resonator for simultaneously dual-mode physical sensing and ppb-level timing

The development of multifunctional MEMS resonators has long been constrained by the challenge of integrating high-sensitivity sensing and high-stability frequency referencing into a single compact device. This limitation hinders the realization of advanced microsystems for precision sensing, navigation, and signal processing. This paper reports a novel MEMS resonator tailored for the emerging blue-sideband excitation (BSE) scheme, enabling simultaneous multi-mode actuation within a modest frequency band and inducing intricate nonlinear mode coupling. The device serves as an ideal platform to study BSE-induced mode interactions and amplifies the merits of BSE due to its intrinsic clustered vibration modes around 300 kHz. Featuring a dual-cosine structure, the resonator yields abundant in-plane flexural modes while retaining a capacitive transduction mechanism and the standard SOI manufacturing process. Compared to conventional designs such as clamped-clamped (C-C) beams or double-ended tuning forks (DETF), this device achieves multi-mode operation without requiring MHz frequencies or large spans, making its multi-modal response essential for multi-parameter measurements and multifunctional applications. This work ascertains the device's basic characterizations, including temperature effects, electrostatic perturbation sensitivity, and noise floor, when subjected to the BSE scheme. Notably, some modes exhibit counter-intuitive positive frequency shifts with rising temperatures, enabling stabilization via mode summation. Experimentally, a single mode functions as a sensor with a maximum sensitivity of 39.6 mV/V and a noise floor of 1.9 μV/√Hz (Frequency-mode sensing), while the sum frequency of two modes provides a stable reference with 1.5 ppb at 1000 s (Amplitude-mode sensing). Even under combined temperature and electrostatic disturbances, long-term stability remains around 11.9 ppb at 1000 s. These results demonstrate the dual-mode sensing and referencing capabilities of the proposed resonator, addressing fundamental limitations in current MEMS designs and paving the way for advanced, integrated microsystem applications. The development of multifunctional MEMS resonators has long been constrained by the challenge of integrating high-sensitivity sensing and high-stability frequency referencing into a single compact device. This limitation hinders the realization of advanced microsystems for precision sensing, navigation, and signal processing. This paper reports a novel MEMS resonator tailored for the emerging blue-sideband excitation (BSE) scheme, enabling simultaneous multi-mode actuation within a modest frequency band and inducing intricate nonlinear mode coupling. The device serves as an ideal platform to study BSE-induced mode interactions and amplifies the merits of BSE due to its intrinsic clustered vibration modes around 300 kHz. Featuring a dual-cosine structure, the resonator yields abundant in-plane flexural modes while retaining a capacitive transduction mechanism and the standard SOI manufacturing process. Compared to conventional designs such as clamped-clamped (C-C) beams or double-ended tuning forks (DETF), this device achieves multi-mode operation without requiring MHz frequencies or large spans, making its multi-modal response essential for multi-parameter measurements and multifunctional applications. This work ascertains the device's basic characterizations, including temperature effects, electrostatic perturbation sensitivity, and noise floor, when subjected to the BSE scheme. Notably, some modes exhibit counterintuitive positive frequency shifts with rising temperatures, enabling stabilization via mode summation. Experimentally, a single mode functions as a sensor with a maximum sensitivity of 39.6 mV/V and a noise floor of 1.9 μV/√Hz (Frequency-mode sensing), while the sum frequency of two modes provides a stable reference with 1.5 ppb at 1000 s (Amplitude-mode sensing). Even under combined temperature and electrostatic disturbances, long-term stability remains around 11.9 ppb at 1000 s. These results demonstrate the dual-mode sensing and referencing capabilities of the proposed resonator, addressing fundamental limitations in current MEMS designs and paving the way for advanced, integrated microsystem applications.