A novel approach to the analysis of squeezed-film air damping in microelectromechanical systems

Abstract

Squeezed-film damping (SFD) is a phenomenon that significantly affects the performance of micro-electro-mechanical systems (MEMS). The total damping force in MEMS mainly include the viscous damping force and elastic damping force. Quality factor (Q factor) is usually used to evaluate the damping in MEMS. In this work, we measure the Q factor of a resonator through experiments in a wide range of pressure levels. In fact, experimental characterizations of MEMS have some limitations because it is difficult to conduct experiments at very high vacuum and also hard to differentiate the damping mechanisms from the overall Q factor measurements. On the other hand, classical theoretical analysis of SFD is restricted to strong assumptions and simple geometries. In this paper, a novel numerical approach, which is based on lattice Boltzmann simulations, is proposed to investigate SFD in MEMS. Our method considers the dynamics of squeezed air flow as well as fluid-solid interactions in MEMS. It is demonstrated that Q factor can be directly predicted by numerical simulation, and our simulation results agree well with experimental data. Factors that influence SFD, such as pressure, oscillating amplitude, and driving frequency, are investigated separately. Furthermore, viscous damping and elastic damping forces are quantitatively compared based on comprehensive simulation. The proposed numerical approach as well as experimental characterization enables us to reveal the insightful physics of squeezed-film air damping in MEMS.

Directional Passive Transport of Microdroplets in Oil-Infused Diverging Channels for Effective Condensate Removal

“…In parallel with theoretical analysis, the process of capillary-driven and coalescence-enhanced droplet motion in a diverging channel was simulated by using the lattice Boltzmann method (Section S4.2, Supporting Information). , The simulation results directly show the pressure gradient inside the stretched droplet with a front–back curvature difference. The streamlines indicate the detailed droplet motion direction along the channel.…”

Theoretical and Simulation Studies on Designing a Phase-Reversal-Based Broadband CMUT With Flat Passband and Improved Noise Rejections for SHM

“…Based on the classical theoretical analysis [20], the squeeze-film damping can be evaluated quickly. However, the accuracy cannot be guaranteed due to strong assumptions (e.g., rigid body motion and small structural displacements) [26]. A numerical approach may be required to predict the squeeze-film damping accurately, e.g., the finite element simulation [finite element method (FEM)] or the lattice Boltzmann simulation reported in [26].…”

“…However, the accuracy cannot be guaranteed due to strong assumptions (e.g., rigid body motion and small structural displacements) [26]. A numerical approach may be required to predict the squeeze-film damping accurately, e.g., the finite element simulation [finite element method (FEM)] or the lattice Boltzmann simulation reported in [26]. The structural parameters of a CMUT cell are represented by the definitions shown in Table I.…”

Thermal Lattice Boltzmann Simulation of Evaporating Thin Liquid Film for Vapor Generation

“…Besides, LBM employs a simple algorithm (collision and streaming), which makes it intrinsically scalable and parallelizable for computations. LBM has been used in many engineering and scientific problems, e.g., [14][15][16][17][18][19][20]. In this paper, we will show that LBM, and more specifically thermal LBM (TLBM), can reproduce several important phenomena in TFE, even without very fine mesh grids.…”