The fairy world of quartz vibrating MEMS

Chen

et al. 2020

Sensors

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: Resonant Mems Accelerometers With Frequency Readoutmentioning

confidence: 99%

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

Chen

et al. 2020

Sensors

“…These simulated sensitivities are then compared on sensitivity measured on four magnetometer prototypes. For the last three decades, quartz resonators are used in inertial and frequency/time measurements [18]. This study is directly derived of these previous studies.…”

Section: Experimental Validationmentioning

confidence: 99%

Optimization of an MEMS Magnetic Thin Film Vibrating Magnetometer

et al. 2017

Self Cite

This paper presents models developed through analytical or numerical computation and finite element analysis to improve the resolution of a new kind of vibrating magnetometers. This peculiar magnetometer uses the piezoelectric transduction to actuate a quartz resonator at its resonance frequency taking advantage of the high Q factor of a quartz resonator to achieve high resolution. The magnetic sensitive element is a thin ferromagnetic film of Nickel-Cobalt which is sputtered on the moving beams of the resonator. This magnetic thin film applies a periodic torque on the resonator, shifting its resonance frequency. This torque depends on the magnetic field applied; therefore the value of the magnetic field can be deduced from the frequency shift measurement. The aim of this paper is to develop and improve sensitivity models which will be useful tools in a future work to establish the optimal geometry for a resonator and the best position of the magnetic thin film on it in order to improve the sensitivity and resolution of the global sensor.

“…However, quartz has excellent properties, such as outstanding piezoelectric properties, low temperature coefficient, offers good electric insulation, and allows optical transmission in the wavelength range of UV light. These features have favored the utilization of quartz as a substrate for the fabrication of several types of MEMS, such as resonators [ 1 ], tuning-fork probes [ 2 ] or microlenses [ 3 ], particularly in the field of vibrating inertial sensors—i.e., vibrating beam accelerometer (VBA) [ 4 , 5 , 6 , 7 ] and Coriolis vibrating gyro (CVG) [ 7 , 8 , 9 , 10 , 11 ], based on a resonator as sensitive element.…”

Section: Introductionmentioning

confidence: 99%

Surface Roughness of Z-Cut Quartz Etched by Ammonium Bifluoride and Ammonium Bifluoride Mixed with Isopropyl Alcohol Solutions

Zhang

Tang

et al. 2017

Micromachines

It is meaningful to study the surface morphology of monocrystalline material, but there are few studies on the surface roughness of quartz. So, surface roughness of Z-cut quartz etched by pure ammonium bifluoride and ammonium bifluoride mixed with isopropyl alcohol (IPA) solution was investigated for the first time in this paper. Firstly, when etching in pure ammonium bifluoride solutions, the surface roughness change with etching time, etching temperature, and solution concentration were studied. Then, the surface roughness improvement given by isopropyl alcohol solution was analyzed carefully. The experimental results indicated that: the surface roughness of Z-cut quartz (0001) plane increased with etching time, but decreased with etching temperature and solution concentration; the adding of isopropyl alcohol in ammonium bifluoride solution could decrease the roughness and improve the surface quality. This is the first systemic research of the evolution of quartz surface roughness when etching in ammonium bifluoride solution, and will benefit the future design and manufacture of quartz MEMS devices.