A New Z-axis Resonant Micro-Accelerometer Based on Electrostatic Stiffness

Abstract

Presented in the paper is the design, the simulation, the fabrication and the experiment of a new z-axis resonant accelerometer based on the electrostatic stiffness. The new z-axis resonant micro-accelerometer, which consists of a torsional accelerometer and two plane resonators, decouples the sensing movement of the accelerometer from the oscillation of the plane resonators by electrostatic stiffness, which will improve the performance. The new structure and the sensitive theory of the acceleration are illuminated, and the equation of the scale factor is deduced under ideal conditions firstly. The Ansys simulation is implemented to verify the basic principle of the torsional accelerometer and the plane resonator individually. The structure simulation results prove that the effective frequency of the torsional accelerometer and the plane resonator are 0.66 kHz and 13.3 kHz, respectively. Then, the new structure is fabricated by the standard three-mask deep dry silicon on glass (DDSOG) process and encapsulated by parallel seam welding. Finally, the detecting and control circuits are designed to achieve the closed-loop self-oscillation, to trace the natural frequency of resonator and to measure the system frequency. Experimental results show that the new z-axis resonant accelerometer has a scale factor of 31.65 Hz/g, a bias stability of 727 μg and a dynamic range of over 10 g, which proves that the new z-axis resonant micro-accelerometer is practicable.

A Subnano-g Electrostatic Force-Rebalanced Flexure Accelerometer for Gravity Gradient Instruments

“…Furthermore, two opposite feedback voltages are applied to the two fixed capacitor plates to generate a difference of potential between the proof mass and the fixed plates, in order to restore the proof mass to its null position. Those voltages would contribute to an electrostatic field between the proof mass and the fixed plates, and yield an electrostatic feedback force on the proof mass [ 21 , 22 , 23 , 24 ]: where is the root mean square (RMS) value of the pumping voltage . The first item in Equation (4) is the effective electrostatic feedback force, and hence the output acceleration can be written as …”

Design and Analysis of a New Hair Sensor for Multi-Physical Signal Measurement

“…The torsional movement is converted into a frequency variation by the resonator and the electrostatic coupling combs [15]. The relationship between the moment and the frequency is: $f\approx f_0+SM$ where S is the sensitivity coefficient from the moment to the frequency and: $S=\frac{n\epsilon L{V}^{2}B}{4{\pi }^2{f}_0{d}_1^3{m}_r{k}_o}$ where n is the number of coupling combs, L is the length of coupling combs, V is the bias voltage applied on the coupling combs, B is the equivalent distance from the electrostatic coupling combs to the z -axis (shown in Figure 1A), d 1 is the coupling combs gap and d 1 << d 2 , m r is the proof mass of resonator, f 0 is the static frequency of the resonator and: $f_0=\frac{1}{2\pi }\sqrt{\frac{(k_r-\frac{2n\epsilon L{V}^{2}H}{d_1^3})}{m_r}}$ where k r is the stiffness of resonator and H is the comb thickness.…”

Design of a new differential silicon resonant accelerometer with dual proofmasses using two-stage microlever

“…Micromechanical resonant accelerometers have been widely used in high-precision measurement applications because of their distinctive advantages, such as direct frequency signal output, high sensitivity, stable performance and high resolution [1][2][3]. Microlever mechanisms, including single-stage and multi-stage, are very useful in micromechanical devices in order to transfer an input force/displacement to an output to achieve mechanical and structural improvement.…”