A High-Precision and High-Bandwidth MEMS-Based Capacitive Accelerometer

Chen

et al. 2020

Sensors

Self Cite

This paper reviews the research and development of micromachined accelerometers with a noise floor lower than 1 µg/√Hz. Firstly, the basic working principle of micromachined accelerometers is introduced. Then, different methods of reducing the noise floor of micromachined accelerometers are analyzed. Different types of micromachined accelerometers with a noise floor below 1 µg/√Hz are discussed. Such sensors can mainly be categorized into: (i) micromachined accelerometers with a low spring constant; (ii) with a large proof mass; (iii) with a high quality factor; (iv) with a low noise interface circuit; (v) with sensing schemes leading to a high scale factor. Finally, the characteristics of various micromachined accelerometers and their trends are discussed and investigated.

Section: Mems Accelerometers With a Low Noise Interface Circuitmentioning

confidence: 99%

“…Utz et al [55] (2018) at the Fraunhofer Institute for Microelectronic Circuits and Systems also developed a capacitance to voltage ASIC with an input noise of 50 zF/…”

Section: Mems Accelerometers With a Low Noise Interface Circuitmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

mentioning

confidence: 99%

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Micromachined Accelerometers with Sub-µg/√Hz Noise Floor: A Review

Chen

et al. 2020

Sensors

Self Cite

“…The spring-mass-system area of small capacitive sensors amounts to around 500 × 500 µm 2 to achieve mg resolution and 1 × 1 mm 2 to achieve a resolution of µg [ 4 ]. To reach ng resolution, a large proof mass of several 1 × 1 mm 2 is necessary [ 10 ]. An ultraminiaturized piezoresistive accelerometer with a flexible structure of 387 × 387 µm 2 was published by Park et al [ 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Development and Proof of Concept of a Miniaturized MEMS Quantum Tunneling Accelerometer Based on PtC Tips by Focused Ion Beam 3D Nano-Patterning

Haub

Bogner

Guenther

et al. 2021

Sensors

Most accelerometers today are based on the capacitive principle. However, further miniaturization for micro integration of those sensors leads to a poorer signal-to-noise ratio due to a small total area of the capacitor plates. Thus, other transducer principles should be taken into account to develop smaller sensors. This paper presents the development and realization of a miniaturized accelerometer based on the tunneling effect, whereas its highly sensitive effect regarding the tunneling distance is used to detect small deflections in the range of sub-nm. The spring-mass-system is manufactured by a surface micro-machining foundry process. The area of the shown polysilicon (PolySi) sensor structures has a size smaller than 100 µm × 50 µm (L × W). The tunneling electrodes are placed and patterned by a focused ion beam (FIB) and gas injection system (GIS) with MeCpPtMe3 as a precursor. A dual-beam system enables maximum flexibility for post-processing of the spring-mass-system and patterning of sharp tips with radii in the range of a few nm and initial distances between the electrodes of about 30–300 nm. The use of metal–organic precursor material platinum carbon (PtC) limits the tunneling currents to about 150 pA due to the high inherent resistance. The measuring range is set to 20 g. The sensitivity of the sensor signal, which depends exponentially on the electrode distance due to the tunneling effect, ranges from 0.4 pA/g at 0 g in the sensor operational point up to 20.9 pA/g at 20 g. The acceleration-equivalent thermal noise amplitude is calculated to be 2.4–3.4 mg/. Electrostatic actuators are used to lead the electrodes in distances where direct quantum tunneling occurs.

Advanced Sensor Research

Ultrahigh‐Temperature Piezoelectric Crystal YbBa₃(PO₄)₃ for Vibration Sensing Application

Fan

Sun³

et al. 2023

High‐temperature vibration sensors are of great importance for accurate monitoring of dynamic mechanical conditions in automotive, aerospace and energy‐generation‐related systems. Currently, piezoelectric crystals with ultrahigh operational temperature and good piezoelectric performance for high‐temperature sensing applications are attracting considerable attention. Herein, a novel piezoelectric crystal YbBa3(PO4)3 with cubic symmetry and a high melting point of ≈1850 °C is explored, and grown by using the Czochralski method. The temperature‐dependent behaviors of electro‐elastic constants and electrical resistivity are investigated ranging from 25 to 800 °C, where the dielectric loss of the YbBa3(PO4)3 crystal is found to be ≈15% at 800 °C. In addition, an optimal crystal cut with a pure thickness shear vibration mode is designed. The optimal crystal cut presents a good piezoelectric activity ( = 12.6 pC N−1) as well as good temperature stability. Furthermore, a high‐temperature accelerometer with shear piezoelectric mode is designed and fabricated using the YbBa3(PO4)3 crystal, and the sensing performance at elevated temperature are evaluated. The average sensitivity is found to be 1.16 pC g−1, with a small temperature deviation (≈7.7%), exhibiting a good temperature stability. All these results indicate that YbBa3(PO4)3 piezoelectric crystal is a promising candidate for high‐temperature piezoelectric sensing applications.