A broad-band silicon microseismometer with 0.25 NG/rtHz performance

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: Mems Accelerometers With Novel Mechanical Designmentioning

confidence: 99%

“…Photographs of the first version of MEMS accelerometers developed by Pike et al at Imperial College: (a) first-generation MEMS accelerometer[27], (b) latest version[32].…”

mentioning

confidence: 99%

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

Chen

et al. 2020

Sensors

“…In these tests no reference seismometer was available. Therefore, a purely seismic component cannot be removed from the microseismometer acceleration to calculate the Delta Noise (4), and so the temperature dependent acceleration, a µST , was approximated by the sensor output. This is a reasonable assumption as the low frequency ambient seismic signal is much less than the microseismometer's output when subjected to large temperature variation.…”

Section: Validation Of the Microseismometer Thermal Compensation Amentioning

confidence: 99%

“…These co-located sensors will provide valuable data for the understanding of the internal structure and geophysical processes at play on Mars. Our MEMS microseismometer is implemented as the short period sensor for the mission, however, it has been demonstrated to have a broad-band performance with a sub nano-g noise floor [2] [3] [4]. The capabilities for deployment are limited, due to the constrained power and mass.…”

Section: Introductionmentioning

confidence: 99%

Full-Band Signal Extraction From Sensors in Extreme Environments: The NASA InSight Microseismometer

et al. 2018

Physically meaningful signal extraction from sensors deployed in extreme environments requires a combination of attenuation of confounding inputs and the removal of their residual using decorrelation techniques. In space applications where the resources for physical attenuation are limited, there is a necessity to apply the most effective post-processing analysis available. This paper describes the extraction of the seismic signal from a MEMS microseismometer to be deployed on the surface of Mars. The signal processing, which covers the full bandwidth 1 × 10 −5 Hz to 40 Hz, uses a novel application of sensor fusion through an indirect Kalman Filter in combination with a thermal model of the microseismometer to remove the aseismic contribution of temperature over the frequency range. Owing to the full-band decorrelation, the analysis (based on pre-landing testing in analogous scenarios) produces both a characterisation of the microseismomter and a signal processing approach for information retrieval on Mars, along with other planetary and terrestrial planetary deployments.

“…Pike et al 6,7 presented a mass/spring-based accelerometer with resonance frequencies ranging from 0.1 Hz to 12 Hz. Impressive resolution figures are presented, 2 ng= ffiffiffiffiffiffi Hz p 6 and 0.25 ng= ffiffiffiffiffiffi Hz p 7 .…”

Section: Introductionmentioning

confidence: 99%

High-resolution MEMS inertial sensor combining large-displacement buckling behaviour with integrated capacitive readout

et al. 2019

Commercially available gravimeters and seismometers can be used for measuring Earth's acceleration at resolution levels in the order of ng= ffiffiffiffiffiffi Hz p (where g represents earth's gravity) but they are typically high-cost and bulky. In this work the design of a bulk micromachined MEMS device exploiting non-linear buckling behaviour is described, aiming for ng= ffiffiffiffiffiffi Hz p resolution by maximising mechanical and capacitive sensitivity. High mechanical sensitivity is obtained through low structural stiffness. Near-zero stiffness is achieved through geometric design and large deformation into a region where the mechanism is statically balanced or neutrally stable. Moreover, the device has an integrated capacitive comb transducer and makes use of a high-resolution impedance readout ASIC. The sensitivity from displacement to a change in capacitance was maximised within the design and process boundaries given, by making use of a trench isolation technique and exploiting the large-displacement behaviour of the device. The measurement results demonstrate that the resonance frequency can be tuned from 8.7 Hz-18.7 Hz, depending on the process parameters and the tilt of the device. In this system, which combines an integrated capacitive transducer with a sensitivity of 2.55 aF/nm and an impedance readout chip, the theoretically achievable system resolution equals 17.02 ng= ffiffiffiffiffiffi Hz p. The small size of the device and the use of integrated readout electronics allow for a wide range of practical applications for data collection aimed at the internet of things.