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The deep reactive ion etching (DRIE) process is commonly used for fabricating the MEMS resonators, which sometimes causes the profile of the resonator capacitor inclined. This nonideal feature significantly affects the motion stability of the resonator. In present work, for different inclination angles, the reliable operation conditions of the MEMS disk resonator for step inertial signal and pulse inertial signal are analyzed using the energy method. The dependence of the critical inertial acceleration on inclination angle and testing signal level is given both in expressions and curves. The results show that for a step inertial signal, the reliable operation range of the resonator with an inclination angle of 0.1° is larger than that of 0.25° by a factor of 2.32 for the same testing signal level, and for a pulse inertial signal, the factor is 2.29. With the increase of the inclination angle, the motion stability of the resonators becomes more and more enhanced. This results can provide a theoretical basis for the design of MEMS disk resonator working in the dynamic inertial environment. [ABSTRACT FROM AUTHOR]

This paper is the follow-up of the research we conduct to improve the self-calibration precision of high-precision MEMS capacitive accelerometers. In the previous published study, we have analyzed the influence of DRIE fabrication error on the dynamic self-calibration. In this paper, the influence of fringe effect on the self-calibration is discussed in order to improve the self-calibration precision further more, and the results has proved the feasibility of this self-calibration technique. Aimed at the capacitive accelerometer in this paper, the self-calibration error is only 0.18 % in closed-loop circuit, which is approach to the absolute calibration error of laser interferometer (0.5-1 %), which can satisfy the demand of high-precision sensors. In open-loop circuit, the fringe effect influences the self-calibration obviously and the error reaches 24.2 %, but it can be reduced to 1.49 % by correcting the actuation voltage. The method proposed in this paper may be used to develop full-automatic self-calibration system integrated on circuit board in the future. [ABSTRACT FROM AUTHOR]

For a super high precision MEMS sensor with the comb capacitor structure, the fringe effect of capacitors can not be neglected. In this paper, directing at the comb capacitor structure with slot holes, the effects of the non-overlap parts of comb capacitor, the distance between two slot holes in comb electrodes and slot depth aspect ratio on sensing capacitance are simulated by 3D finite element method of ANSOFT Maxwell software. The results show that when the width H and thickness t of sensing electrode plate are fixed, the fringe effect becomes larger for a smaller length L. The fringe effect is very small as non-overlap length is between 100 μm and 180 μm for 500 μm≤L≤1200 μm. The capacitance error caused by the fringe effect is the smallest for the slot distance 35 μm, slot depth 25 μm and slot width 20 μm. The error of sensing displacement caused by the fringe effect of the comb capacitor is 0.61% obtained by MATLAB Simulink. [ABSTRACT FROM PUBLISHER]

This paper discusses the vibration-induced error in non-ideal MEMS tuning fork gyroscopes (TFGs). Ideal TFGs which are thought to be immune to vibrations do not exist, and imbalance between two gyros of TFGs is an inevitable phenomenon. Three types of fabrication imperfections (i.e., stiffness imbalance, mass imbalance, and damping imbalance) are studied, considering different imbalance radios. We focus on the coupling types of two gyros of TFGs in both drive and sense directions, and the vibration sensitivities of four TFG designs with imbalance are simulated and compared. It is found that non-ideal TFGs with two gyros coupled both in drive and sense directions (type CC TFGs) are the most insensitive to vibrations with frequencies close to the TFG operating frequencies. However, sense-axis vibrations with in-phase resonant frequencies of a coupled gyros system result in severe error outputs to TFGs with two gyros coupled in the sense direction, which is mainly attributed to the sense capacitance nonlinearity. With increasing stiffness coupled ratio of the coupled gyros system, the sensitivity to vibrations with operating frequencies is cut down, yet sensitivity to vibrations with in-phase frequencies is amplified. [ABSTRACT FROM AUTHOR]