Due to compact size, high consistency, and resistance to radio frequency interference, MEMS microphones are increasingly important in the consumer electronics market and have driven the development of intelligent applications. There is a growing demand for enhanced performance in MEMS microphones. Currently, research on the shell design of MEMS microphones is relatively shallow, often only considering the accommodation of the vibrating diaphragm and ASIC chip, as well as the minimization of volume, without focusing on the impact of the shell configuration on the microphone's acoustic performance. Therefore, this paper starts from the perspective of optimizing acoustic response and studies the impact of the packaging shell configuration and design parameters of MEMS microphones on the microphone's sensitivity and frequency response, including the sound collection hole diameter, chamber volume, and chip layout. The goal is to establish a quantitative relationship between these key parameters and the microphone's performance. Simulation software was used to simulate the acoustic characteristics of the microphone shell, and optimal design parameters were recommended based on the simulation results. In addition, the research also proposes methods to adjust the frequency response of the microphone within the target frequency range, providing a reference direction for the scientific design of the shell structure to reduce the transmission loss of acoustic energy and enhance response sensitivity.
Currently, research on Micro-Electro-Mechanical Systems (MEMS) microphone dust protection meshes has predominantly focused on dust prevention capabilities, with scant attention given to acoustic performance, and there is a lack of systematic studies on the patterns of acoustic performance variation. This study utilizes finite element analysis to investigate the impact of structural parameters such as perforation radius, perforation rate, number of perforations, and perforation distribution patterns, as well as material properties like the density of the expanded-polytetrafluoroethylene(e-PTFE) membrane, on acoustic impedance and sound transmission loss. It was found that, at a constant perforation rate, a larger perforation radius results in lower acoustic impedance and sound transmission loss. This research provides a theoretical basis for the subsequent design of MEMS microphone dust protection meshes. Furthermore, an intelligent dust protection device based on metasurfaces has been proposed, which achieves an organic integration of dust prevention and sound wave control functions, and exhibits high sensitivity and robustness, laying the foundation for the development of future smart auditory technologies.
An electromagnetically actuated dual-axis MEMS scanning micromirror for lidar applications is introduced, besides a novel radial magnetic field actuation system is designed. The dual-axis scanning micromirror with large aperture which the plate size of 2.6 mm in diameter was realized utilizing patterned single-turn electroplated copper coils, which combined with a concentric permanent magnet assembly forming radial magnetic field. Based on the basic of this working principle, the displacement response outputs of different torsion beam structures were compared by theoretical analysis and finite element simulation. The serpentine elastic beam was chosen as the external torsion axis of the micromirror device because of its large displacement output. The coupling magnetic field of the permanent magnet assembly was analyzed and simulated to achieve the maximum magnetic field intensity at the coils. Horizontal resonance frequency of the presented micromirror was 3376.2 Hz and vertical resonance frequency was 419.46 Hz, in addition, maximum deflection angle of approximately ±25.2°in horizontal direction and about ±17.4°in vertical direction were achieved at resonance. The design of the micromirror meets the requirements of MEMS lidar for large mirror size and wide scanning field of view.
Resonant pressure sensors are widely used in high precision pressure measurement, but they are mainly focused on the measurements of absolute pressure at present. The fluctuation of atmospheric pressure disturbs the accuracy of gauge pressure sensor. Therefore, a resonant gauge pressure sensor with a double-ended tuning fork resonator is proposed based on wafer level anodic bonding method. To sense the gauge pressure with high accuracy when the resonator is set inside the diaphragm, a novel composite diaphragm structure is proposed with the glass vacuum package layer involved in the pressure-lead diaphragm deflection. The resonator is laterally electromagnetically driven to symmetry mode and electromagnetically detected. With finite element analysis simulation, the effects of several key factors on the measuring accuracy of gauge pressure sensor are discovered and optimized. Research results show that the frequency detection error caused by the fluctuation of atmospheric pressure is reduced by changing the area of bonded area above the resonator and the glass thickness. The simulated non-linearity of proposed sensor after quadratic polynomial fitting is less than 0.01% FS with the pressure range of 0-2.5 MPa, and its measuring sensitivity is up to 3996.6 Hz/MPa.
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