A MEMS Accelerometer for Sub-mG Sensing

Yamane, Daisuke; Konishi, Toshifumi; Safu, Teruaki; Toshiyoshi, Hiroshi; Sone, Masato; Machida, Katsuyuki; Ito, Hiroyuki; Masu, Kazuya

doi:10.18494/sam.2019.2122

Cited by 10 publications

(8 citation statements)

References 21 publications

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“…The noise level improvements that are required for real application are in the range of 10 5 for the accelerometer and 10 4 for the gyroscope. Although recently developed accelerometers and gyroscopes achieve these low noise levels, they are designed to measure signals in the mg-range and are far too delicate for the application at hand [10,23,32]. If developments continue to progress rapidly, and a robust sensor with low noise level and high measurement range is developed, our method could be applied in a real setting.…”

Section: Discussionmentioning

confidence: 99%

Rigid and non-rigid motion compensation in weight-bearing cone-beam CT of the knee using (noisy) inertial measurements

Maier¹,

Nitschke²,

Choi³

et al. 2021

Preprint

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Involuntary subject motion is the main source of artifacts in weight-bearing cone-beam CT of the knee. To achieve image quality for clinical diagnosis, the motion needs to be compensated. We propose to use inertial measurement units (IMUs) attached to the leg for motion estimation. We perform a simulation study using real motion recorded with an optical tracking system. Three IMU-based correction approaches are evaluated, namely rigid motion correction, non-rigid 2D projection deformation and non-rigid 3D dynamic reconstruction. We present an initialization process based on the system geometry. With an IMU noise simulation, we investigate the applicability of the proposed methods in real applications. All proposed IMUbased approaches correct motion at least as good as a state-of-the-art marker-based approach. The structural similarity index and the root mean squared error between motion-free and motion corrected volumes are improved by 24-35% and 78-85%, respectively, compared with the uncorrected case. The noise analysis shows that the noise levels of commercially available IMUs need to be improved by a factor of 10 5 which is currently only achieved by specialized hardware not robust enough for the application. The presented study confirms the feasibility of this novel approach and defines improvements necessary for a real application.

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Section: Discussionmentioning

confidence: 99%

Rigid and non-rigid motion compensation in weight-bearing cone-beam CT of the knee using (noisy) inertial measurements

Maier¹,

Nitschke²,

Choi³

et al. 2021

Preprint

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“…Due to the proof mass made with a single material, the induced internal stress is equal to zero, as in [13], producing no serious effect of temperature stress on the proof mass, subsequently increasing the robustness of the structure against temperature variations. In Table 5, the error between analytical and simulation values is also shown.…”

Section: Characteristic Equations For Complete Accelerometer With Symmentioning

confidence: 99%

“…The authors of [11,12] provide voltage sensitivities of 0.24 and 3.16 V/g, respectively. Capacitive sensitivity is reported by [13,14] of 3.3 pF/G and 15.5 fF/g, respectively. Finally, mechanical sensitivity is given by [14,15] of 0.574 µm/g and 29.8 nm/g, respectively.…”

Section: Introductionmentioning

confidence: 98%

Capacitive Accelerometers with Beams Based on Alternated Segments of Different Widths

et al. 2020

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Microelectromechanical (MEM) Accelerometers measure the accelerations or vibrations experienced by objects due to inertial forces or mechanical excitations. To improve their proof mass displacement, several alternatives have been used, such as the design of different shapes of suspension beams. In this work, a new shape of beam is proposed based on alternated segments of different widths. To analyze its performance, one-quarter, middle and complete accelerometers were calculated and simulated; the results were compared with similar cases using conventional uniform-shaped beams. A notable improvement in the proof mass displacement was obtained in all cases, especially with the proposed symmetrical-shaped beam. Harmonic response and explicit dynamic analysis were also considered to discover performance when they are subjected to structural load. An improvement in amplitude displacement was also observed, as well as operation frequency reduction. From the explicit dynamic analysis, a faster performance of the accelerometer with uniform arms can be observed; however, it responds at a lower range of input velocities. A performance comparison of the proposed beam is presented considering the two reported accelerometers. Finally, from the variation in the width of the thinner segment of the symmetrical arms, it can be observed that it is possible to obtain an increment in the displacement of the proof mass of 39.57% and a decrement in natural frequency of 15.30%, with respect to the case of the uniform arm. Other advantages of the symmetric beam are the stress distribution, reducing its effect on the proof mass, as well as their low cross-axis sensitivity. Simulations were performed with ANSYS.

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“…To increase the sensitivity of an accelerometer, the ratio of the proof mass to the supporting beam stiffness should be increased [7]. The total noise equivalent acceleration (TNEA) is calculated as [8,9]:…”

Section: Introductionmentioning

confidence: 99%

Analytical modeling of an inclined folded-beam spring used in micromechanical resonator devices

Rahbar Ranji,

Li,

Alirezaee

et al. 2023

Eng. Res. Express

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Accurate estimation of the mechanical behavior of springs is crucial for the proper design of Microelectormechanical systems (MEMS). The main objective of this study is to derive a closed-form equation for the calculation of the stiffness of an inclined spring in the form of folded beams. The energy-based method was used to calculate the displacements of a folded beam that was fixed at one end and giuded at the other end. The analytical model was then compared with the finite element method using ANSYS for different inclination angles of the folded beam spring, showing good agreement. The angle on inclination has changed from zero to 180 degress, and stiffness of folded beam is detemined. The derived expressions of the compliances were checked for the case of serpentine springs with inclination angle of zero, and different length ratios against the literature. It is found that neglecting small lengths for calculating the stiffness of the folded beam spring is not justified. The influential geometrical parameters, including different lengths of the spring and inclination angle of the spring, on the stiffness are studied. It is found that the angle of inclination of the principal axes of spring constants depends on the geometrical parameters, and the angle of inclination has more effect on the stiffness of a folded beam spring than the number of folds.

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A MEMS Accelerometer for Sub-mG Sensing

Cited by 10 publications

References 21 publications

Rigid and non-rigid motion compensation in weight-bearing cone-beam CT of the knee using (noisy) inertial measurements

Rigid and non-rigid motion compensation in weight-bearing cone-beam CT of the knee using (noisy) inertial measurements

Capacitive Accelerometers with Beams Based on Alternated Segments of Different Widths

Analytical modeling of an inclined folded-beam spring used in micromechanical resonator devices

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