The reduction of temperature effect is vitally important for high precision sensors. This paper introduces the theoretical analysis and experimental verification of an in-situ compensation method on the temperature coefficient of the scale factor for a single-axis electromagnetic force-balance feedback MEMS accelerometer. A micro thermistor, fabricated together with the MEMS accelerometer, is integrated to in-situ sense the temperature variation of the accelerometer. The thermistor is connected to the voltage-to-current resistance in series, which compensates the variation of the scale factor of the accelerometer that is influenced by temperature variation. The experimental results reveal that the temperature coefficient of the scale factor of the compensated accelerometer is within 6 ppm/°C for the temperature range from 25°C to 50°C, which is reduced by 68 times compared with the uncompensated accelerometer. Benefiting from the compatible fabrication process and the in-situ compensation, the proposed method is promising to be low-cost and high-efficiency.

High-precision MEMS accelerometers with nano-g resolution are emergent instruments for geophysical applications and proved their competence in terms of functionality. The electromagnetic actuator, which serves as an auxiliary component in nano-g MEMS accelerometers for improving the dynamic response, faces the challenges of process incompatibility, temperature sensitivity, and large form factor. Thereby, this paper proposes an area-changed capacitive method for both displacement transducing and force balance in a nano-g MEMS accelerometer, aiming to address those posed challenges and provide favourable performance. Thanks to the allowed large displacement range in the sensitive direction of the proposed device, the area-changed capacitive mechanism is able to be integrated with a highly-sensitive quasi-zero stiffness spring-mass structure. As a result, the fabricated force-balance MEMS accelerometer attains a calibrated self-noise of 1.3 ng/ $\surd$ Hz, which is one of the most sensitive MEMS-based accelerometers reported to date. The settling time, on the other hand, is reduced to 0.5 s with the electrostatic closed-loop control featuring the proposed subject, compared to 15.7 s in the open-loop configuration. In addition, the critical acceleration input at the boundary of the “pull-in” is calculated as 5.4 g, which is adaptable to most geophysical applications. This work is of considerable potential in geophysical applications such as earthquake monitoring or gravity measurements, and promising a high-performance closed-loop MEMS accelerometer.2023-0161

Capacitive MEMS accelerometers with area-variable periodic-electrode displacement transducers found wide applications in disaster monitoring, resource exploration and inertial navigation. The bonding-induced warpage, due to the difference in the coefficients of thermal expansion of the bonded slices, has a negative influence on the precise control of the interelectrode spacing that is essential to the sensitivity of accelerometers. In this work, we propose the theory, simulation and experiment of a method that can alleviate both the stress and the warpage by applying different bonding temperature on the bonded slices. A quasi-zero warpage is achieved experimentally, proving the feasibility of the method. As a benefit of the flat surface, the spacing of the capacitive displacement transducer can be precisely controlled, improving the self-noise of the accelerometer to 6 ng/√Hz @0.07 Hz, which is about two times lower than that of the accelerometer using a uniform-temperature bonding process.