Mode-localized sensors have attracted attention because of their high parametric sensitivity and first-order common-mode rejection to temperature drift. The high-fidelity detection of resonator amplitude is critical to determining the resolution of mode-localized sensors where the measured amplitude ratio in a system of coupled resonators represents the output metric. Operation at specific bifurcation points in a nonlinear regime can potentially improve the amplitude bias stability; however, the amplitude ratio scale factor to the input measurand in a nonlinear regime has not been fully investigated. This paper theoretically and experimentally elucidates the operation of mode-localized sensors with respect to stiffness perturbations (or an external acceleration field) in a nonlinear Duffing regime. The operation of a mode-localized accelerometer is optimized with the benefit of the insights gained from theoretical analysis with operation in the nonlinear regime close to the top critical bifurcation point. The phase portraits of the amplitudes of the two resonators under different drive forces are recorded to support the experimentally observed improvements for velocity random walk. Employing temperature control to suppress the phase and amplitude variations induced by the temperature drift, 1/f noise at the operation frequency is significantly reduced. A prototype accelerometer device demonstrates a noise floor of 95 ng/√Hz and a bias instability of 75 ng, establishing a new benchmark for accelerometers employing vibration mode localization as a sensing paradigm. A mode-localized accelerometer is first employed to record microseismic noise in a university laboratory environment.

Electrical tuning of bandwidth is critical for microelectromechanical system (MEMS) resonator-based narrowband filters especially at ultra-high frequency ranges and beyond. The resonance frequency of MEMS resonators is highly susceptible to fabrication process uncertainties and very small fabrication variations could result in significant shift in their resonance frequency. Although, disk resonators are the most acceptable candidates for implementing of resonators at GHz frequencies, according to their high stiffness, electrical tuning of these resonators and consequently the resulting filters is almost impossible. This study presents a novel tuning method for low velocity through anchor coupled MEMS radial contour mode disk resonators based on the coupling beam's stiffness tuning using the piezoelectric effect. As the results of this method, high bandwidth tuning ratio as 1:1.25 is achieved due to changing the tuning DC voltage from 0 to 20 V. This impressive result for a narrowband filter with 450 kHz of bandwidth is achieved due to changing the stiffness of low stiff coupling beam which is much easier to control in comparison with extremely high stiffness disk resonators. Various simulation results, as well as analytical works, verify the proposed approach.

Miniaturized physical transducers based on weakly coupled resonators have previously demonstrated the twin benefits of high parametric sensitivity and the first-order common-mode rejection of environmental effects. Current approaches to sensing based on coupled resonator transducers employ strong coupling where modal overlap of the responses is avoided. This strong coupling limits the sensitivity for such mode-localized sensors that utilize an amplitude ratio (AR) output metric as opposed to tracking resonant frequency shifts. In this paper, this limitation is broken through by theoretically and experimentally demonstrating the operation of the weakly coupled resonators in the weak-coupling (modal overlap) regime. Specifically, a prototype MEMS sensor based on this principle is employed to detect shifts in stiffness, with a stiffness bias instability of 10.3μN/m (9.5ppb) and a corresponding noise floor of 7.1μN/m/√Hz (6.8ppb/√Hz). The linear dynamic range of such AR readout sensors is first explored and found to be defined by the dynamic range of the secondary resonator. The proposed method provides a promising approach for high-performance resonant force and inertial sensors.

We present an investigation of the nonlinear dynamics of a microelectromechanical system (MEMS) arch subjected to a combination of AC and DC loadings in the presence of three-to-one internal resonance. The axial force resulting from the residual stress or temperature variation is considered in the governing equation of motion. The method of multiple scales is used to solve the governing equation. A four first-order ordinary differential equation describing the modulation of the amplitudes and phase angles is obtained. The equilibrium solution and its stability of the modulation equations are determined. Moreover, we also obtain the reduced-order model (ROM) of the MEMS arch employing the Galerkin scheme. The dynamic response is presented in the form of time traces, Fourier spectrum, phase-plane portrait, and Poincare sections. The results show that when there is an internal resonance, the energy transfer occurs between the first and third modes. In addition, the response of the MEMS arch presents abundant dynamic behaviors, such as Hopf bifurcation and quasiperiodic motions.

Micro/nano-electromechanical resonator-based logic elements have emerged recently as an attractive potential alternative to semiconductor electronics. The next step for this technology platform to make it into practical applications and to build complex computing operations beyond the fundamental logic gates is to develop cascadable logic units. Such units should produce outputs that can be used as inputs for the next logic units. Despite the recent developments in electromechanical computing, this requirement has remained elusive. Here, we demonstrate for the first time a conceptual framework for cascadable logic units. Cascadability is experimentally demonstrated through two case studies; one by cascading two OR logic gates. The other case is the universal NOR logic gate realized by cascading an OR and a NOT gate. The logic operations are performed by on-demand activation and deactivation of the second mode of vibration of a clamped-clamped microbeam resonator. We show that the demonstrated approach significantly lowers the complexity and number of microresonator-based logic functions compared to the CMOS-based counterparts, which improves energy efficiency. This can potentially lead toward the realization of a novel technology platform for an alternative computing paradigm.