This paper presents a high performance MEMS temperature sensor comprised of a double-ended-tuning-fork (DETF) resonator and strain-amplifying beam structure. The temperature detection is based on the ‘thermal strain induced frequency variations’ of the DETF resonator. The major source of thermal strain leading to the frequency shifts is the difference in thermal expansion coefficients of the substrate and the device layers of the fabricated structures. By selecting the substrate as glass and the device layers as single crystal silicon, i.e. materials with different thermal expansion coefficients, the tines of the resonators are exposed to axial load with the changing temperature, which causes a change in the resonance frequency of the resonators. This resonance frequency shift can be related with the changing temperature by taking the thermal strain relations into consideration, which enables utilization of the resonator as a highly sensitive temperature sensor. The resonators used in this study have been fabricated by utilizing the advanced MEMS process that incorporates the simple silicon-on-glass process with the wafer level vacuum packaging Torunbalci et al (2015 J. Microelectromech. Syst . 24 556–64). The fabricated resonators have been tested in a temperature-controlled oven between −20 °C and 60 °C, and the results of two distinct designs are compared to be able to observe the effectiveness of the strain amplifying beam. Measurement results show that the design with the strain amplifying beam increases the temperature coefficient of frequency of the resonators by 33 times when compared to the one-end free DETF resonators. Minimum detectable temperature variations observed by the resonators used in this study is 0.0011 °C. This kind of very high resolution temperature sensing can be achieved by integrating this MEMS temperature sensor with any type of physical MEMS sensor where its fabrication process includes different materials for the substrate and sensor structures.

This study reports a temperature compensation method for a capacitive MEMS accelerometer by using a MEMS double-ended-tuning-fork (DETF) resonator integrated with the accelerometer structure on the same die. The proposed method utilizes the frequency information of the clamped-clamped DETF resonator which is oscillating in a closed-loop operation. In order to compensate the temperature dependence of the accelerometer output, frequency drift of the DETF resonator against changing temperature is used, i.e., the resonator frequency is used as the temperature data for compensation purposes. On-chip integration of two sensors allows precise temperature sensing abilities by removing the thermal lag between the DETF resonator and the accelerometer. Tests are held in the -20 °C and 60 °C range by operating both sensors simultaneously in a temperature-controlled oven. The measurement results indicate temperature coefficient of frequency (TCf) of 480 ppm/K for the integrated resonator and temperature dependence of 1,164 μg/K for the accelerometer output, which is decreased to 1.4 μg /K after temperature compensation. Improved noise performances indicate the bias instability of 30 μg and the velocity random walk of 24 μg/sqrt(Hz) with the removal of the temperature ramp (after 30 seconds) in Allan-deviation plot.

This paper presents a new, high-performance SOI-MEMS gyroscope with decoupled oscillation modes. The gyroscope structure allows to achieve matched-resonance-frequencies, large drive-mode oscillation amplitude, high sense-mode quality factor, and low mechanical crosstalk, demonstrating a measured noise-equivalent rate of 90 (deg/hr)/Hz1/2even at atmospheric pressure. The angular rate sensitivity of the gyroscope is 100 µ V/(deg/sec) at atmospheric pressure. This value improves to 2.4mV/(deg/sec) at vacuum, for which the measured noise-equivalent rate of the gyroscope reaches to 35 (deg/hr)/Hz1/2. The R2-nonlinearity of the gyroscope is measured to be better than 0.02%. The gyroscope has a low quadrature signal of 70deg/sec and a short-term bias stability of 1.5deg/sec.

This paper presents an analog readout method for capacitive MEMS accelerometers in which the feedback actuation and capacitive detection are achieved simultaneously on the same electrode set. The presented circuit operates in closed-loop for improved linearity, and it is constructed in a hybrid platform package in which off-the-shelf discrete components are used together with the silicon-on-glass micro-accelerometer. The system is developed as a practical solution to reduce the complexity of the readout circuit and the accelerometer without degrading the overall system performance. Experimental results demonstrate 17.5 micro-g per square-root hertz velocity random walk, and 28 micro-g bias instability. Considering the estimated full scale range of 20 g, the dynamic range of the sensor is calculated to be close to 124 dB.