Structural Asymmetry
Microelectromechanical capacitive transducers exhibit non-uniform clearance variations between opposing fixed and movable sense electrodes during high-amplitude proof mass motion. This physical behavior leads directly into asymmetric gap compression, which alters the nominal electrostatic restoring force and distorts output linearity when displacement exceeds ten percent of the baseline gap. Standard wafer fabrication techniques establish initial plate clearance within manufacturing tolerances set at three hundred nanometers.
Viscous Squeeze
Viscous gas film dynamics within micro-machined cavities produce asymmetric damping forces when the distance between parallel sensing surfaces reduces unevenly. During asymmetric gap compression, air or inert gas trapped within the narrowing boundary experiences a steeper pressure gradient than the expanding region on the opposite face, creating an uncompensated net pressure force that biases the central mass. Mechanical shock inputs amplify this mechanism, shifting the mean position of the suspension beam and causing baseline zero-g offset drift across dynamic operating ranges.
Instrument qualification procedures measure this fluid behavior by subjecting packaged accelerometers to controlled acoustic sweeps and high-g centrifuge testing, recording changes in output current against calibrated reference accelerometers.
Harmonic Distortion
Differential read-out electronics processing capacitive currents encounter even-order harmonic distortion under large physical excursions. Sustained asymmetric gap compression generates second-harmonic signal content that bypasses first-order differential rejection networks in front-end application-specific integrated circuits. System integrators suppress these parasitic signals by incorporating closed-loop electrostatic force feedback to maintain uniform gap clearance.
Calibration Bound
Metrological validation relies on single-axis vibration sweeps to determine the boundary where displacement non-linearities surpass defined noise floors. Beyond this threshold, asymmetric gap compression degrades scale factor stability and invalidates small-signal linear transfer functions. Test engineers record calibration factors across temperature steps to certify sensor performance under peak operational loads.
