MEMS Shock Absorbers Integrated with Al₂O₃-Reinforced, Mechanically Resilient Nanotube Arrays

Reliability of MEMS inertial devices in mechanical and thermal environments: A review

“…Three-dimensional (3D) nanoscale lattices have attracted significant attention as structural materials for mechanical energy dissipation due to their excellent mechanical elasticity and high damping capacity [ 55 ]. A vertically aligned 3D nanocomposite based on ceramic-reinforced carbon nanotube (CNT) arrays was proposed by Eunhwan Jo et al for in-plane damping and energy dissipation materials for MEMS with in-plane shock reliability over a wide acceleration range (0–12,000 g) [ 56 ]. In the impact drop test, samples with nanotube arrays had approximately 115% and 80% higher survival rates (average acceleration at rupture of 10,000 g) compared to controls (no nanotubes) with hard-stop and flexible spring dampers, respectively.…”

“… MEMS actuators The optimal shape of MEMS beam (cantilever-mass, beam-comb, beam-island and folded beam) Improvements of 13–79 % in different performance objectives 2022 [ 50 ] MEMS gyroscopes A vertically aligned 3D nanocomposite based on ceramic-reinforced carbon nanotube (CNT) arrays for shock absorbers of gyroscopes The in-plane shock reliability is over a wide acceleration range (0–12,000 g). 2023 [ 56 ] Optimizing the design of MEMS stopper's shape and stiffness The maximum stress of the beam-mass structure was decreased by 70 % 2021 [ 51 ] A structure of Trap-and-Hold (TAH) to effectively restrict the movement of the mass The after-shock Angle Random Walk (ARW) was 0.0483 deg/rt-hr and the in-run bias instability (IrBS) was 0.69 deg/hr. 2020 [ 58 ] Epitaxially encapsulated (EPI) MEMS disc resonating gyroscopes (DRGs) Maximum 50,000g impact with structural integrity and nearly constant resonance frequency (1.34 ppm change) 2020 [ 59 ] Optimizing the thickness of V-shaped beam of quartz tuning forks resonant gyroscope Optimized beam thickness of 80 μm with a maximum stress of 94.721 MPa, which is able to tolerate an shock with an amplitude of 1500 g and a duration of 2 ms. 2020 [ 35 ] Enhancing the equivalent stiffness of the tuning fork gyroscope by restraining the movement of the quality mass Improvement of impact resistance until failure at peak acceleration of 20,000 g and duration of 80 μs.…”

Mechanically resilient, alumina-reinforced carbon nanotube arrays for in-plane shock absorption in micromechanical devices

“…Note that the beam supporting the proof mass is referred to as a microbeam, and the beam colliding with the proof mass is referred to as a spring. We considered three structural concepts utilizing nanocomposites to improve the shock reliability of movable structures, which are referred to as friction-based, fastening-type, and compression-based shock absorbers, respectively, as reported in our previous studies 26,27 . First, we exploit the frictional contact at the interface between the nanocomposite arrays to dissipate the mechanical shock energy by Coulomb damping.…”

Design of a Shock-Protected Structure for MEMS Gyroscopes over a Full Temperature Range

“…Peng et al conducted shape optimization on MEMS cantilevers, comb structures, island beams, and folded beams, resulting in a 13-79% improvement in various shock resistance properties of MEMS inertial devices [14]. In terms of energy dissipation, researchers have proposed various shock absorber materials with a low coefficient of restitution (COR) as contact materials [15]. Eunhwan Jo et al introduced a three-dimensional nano-composite material consisting of a vertically aligned carbon nanotube (CNT) array reinforced with ceramics for in-plane damping and energy dissipation in MEMS devices [16].…”