Silicon Substrate Thermal Expansion Mechanics in Micro Inertial Sensors
Silicon substrate thermal expansion alters MEMS structural spacing and compliance, requiring isolated single-point anchors and 3rd-order ASIC polynomial correction.
Micro-Gimbal Isolation
Vibration Attenuation
Passive mechanical structures designed to filter out high-frequency vibrations before they reach sensitive rotating or tilting platforms ensure high pointing accuracy. Through micro-gimbal isolation, designers protect miniaturized sensors from the high-frequency structural noise that originates from cooling fans or actuator movements. This attenuation is critical for stabilizing scanning mirrors and micro-sensors in dynamic environments.
Gimbal Design
Suspension assemblies are optimized with flexible hinges and damping materials that absorb vibrational energy in specific frequency bands. This structure allows the micro-gimbal isolation system to maintain low transmissibility at frequencies matching the resonance of the scanning mirror. The design of these hinges involves balancing structural flexibility with the mechanical strength needed to survive high shock loads.
Parasitic Coupling
Unwanted torsional forces from electrical wire routing or asymmetric thermal expansion can bypass the isolation structure. This bypass degrades the efficacy of the micro-gimbal isolation by transmitting high-frequency vibrations directly to the sensor platform. Symmetric routing of micro-coaxial cables and the use of isotropic materials for the mounting brackets help minimize these parasitic paths.
Performance Qualification
Characterization of these isolation systems involves driving the mounting structure with a piezoelectric shaker and measuring the resulting platform motion with a laser Doppler vibrometer. This setup allows technicians to calculate the transmissibility curve of the micro-gimbal isolation system across a wide frequency range. The resulting data are used to confirm that the resonance peaks sit well away from the operating frequencies of the sensor.
This verification is essential for ensuring that the sensor can deliver clean data even when subjected to intense structural noise during operation.