Accurate Sensorless Multistable Microsystem With a Single Actuator

Hussein, Hussein; Fariborzi, Hossein

doi:10.3389/fmech.2022.825470

“…are widely used in MEMS as compliant bistable mechanisms. Several mechanisms with interesting behavior at small and large scales have been developed, relying on the special stiffness behavior of pre-shaped beams 27 , including negative stiffness mechanisms 28 , zero-force mechanisms 29 , tunable stiffness mechanisms 30 , large-stroke mechanisms 31 , metamaterials 32 , safe manipulation 33 , accurate positioning 34 , and high sensitivity sensors 21 .…”

Section: Introductionmentioning

confidence: 99%

Near-zero stiffness accelerometer with buckling of tunable electrothermal microbeams

Hussein,

Wang,

Esteves

et al. 2023

Preprint

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Pre-shaped microbeams, curved or inclined, are widely used in MEMS for their interesting stiffness properties. These mechanisms allow a wide range of positive and negative stiffness tuning in their direction of motion. A mechanism of pre-shaped beams with opposite curvature, connected in a parallel configuration, can be electrothermally tuned to reach a near-zero or negative stiffness behavior at the as-fabricated position. The simple structure helps incorporate the tunable spring mechanism in different designs for accelerometers, even with different transduction technologies. The sensitivity of the accelerometer can be considerably increased or tuned for different applications by electrothermally changing the stiffness of the spring mechanism. Opposite inclined beams are implemented in a capacitive micromachined accelerometer. The measurements on fabricated prototypes showed more than 55 times gain in sensitivity compared to their initial sensitivity. The experiments showed promising results in enhancing the resolution of acceleration sensing and the potential to reach unprecedent performance in micromachined accelerometers.

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Near-zero stiffness accelerometer with buckling of tunable electrothermal microbeams

Hussein,

Wang,

Amendoeira Esteves

et al. 2024

Microsyst Nanoeng

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Pre-shaped microbeams, curved or inclined, are widely used in MEMS for their interesting stiffness properties. These mechanisms allow a wide range of positive and negative stiffness tuning in their direction of motion. A mechanism of pre-shaped beams with opposite curvature, connected in a parallel configuration, can be electrothermally tuned to reach a near-zero or negative stiffness behavior at the as-fabricated position. The simple structure helps incorporate the tunable spring mechanism in different designs for accelerometers, even with different transduction technologies. The sensitivity of the accelerometer can be considerably increased or tuned for different applications by electrothermally changing the stiffness of the spring mechanism. Opposite inclined beams are implemented in a capacitive micromachined accelerometer. The measurements on fabricated prototypes showed more than 55 times gain in sensitivity compared to their initial sensitivity. The experiments showed promising results in enhancing the resolution of acceleration sensing and the potential to reach unprecedent performance in micromachined accelerometers.

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Modeling thermal and buckling behavior in electrothermal bimorphs

Hussein,

Tanguy,

Lakkis

et al. 2024

Smart Mater. Struct.

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Buckling is a structural phenomenon that can induce significant motion with minimal input variation. Electrothermal bimorphs, with their simple input and compact design, can leverage out-of-plane buckling motion for a broad range of applications. This paper presents the development of analytical electrothermal and structural models for such bimorphs. The electrothermal model calculates the temperature distribution within the bimorph caused by electrothermal heating, providing a 2D explicit analytical expression for estimating temperature along the bimorph’s length and cross-section. Nonhomogeneous heating leads to varying strains, which induce axial forces and moments along the bimorph’s neutral plane, varying with thermal expansion. The structural model derives the governing equation of deformation for the bimorph by analyzing internal strains and stresses resulting from deformation, electrothermal heating, and residual stresses. An analytical solution for deflection is obtained, incorporating infinite sums of heating and buckling modes, with closed-form equivalent expressions when possible. The bimorph’s behavior under different scenarios of residual stresses and electrothermal heating is elucidated based on the analytical model. Comparisons with Finite Element simulations demonstrated excellent agreement, highlighting the high accuracy of the proposed models.

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Accurate Sensorless Multistable Microsystem With a Single Actuator

Cited by 3 publications

References 41 publications

Near-zero stiffness accelerometer with buckling of tunable electrothermal microbeams

Near-zero stiffness accelerometer with buckling of tunable electrothermal microbeams

Near-zero stiffness accelerometer with buckling of tunable electrothermal microbeams

Modeling thermal and buckling behavior in electrothermal bimorphs

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