Material Relaxation
Suspended micro-machined structures undergo gradual physical position changes under continuous mechanical or electrostatic tension. Proof mass creep alters the neutral resting point of an accelerometer element over extended operating periods. Micro-scale material relaxation occurs within silicon suspension springs, anchor points or metal film coatings.
Position shifts alter baseline capacitive gaps, resulting in uncalibrated zero-g offset drift over time.
Constant Loading
Sustained gravitational acceleration or continuous electrostatic bias forces apply steady stress to MEMS suspension beams. Continuous load application drives slow dislocation movement and grain boundary sliding within structural materials. Creep rates increase exponentially with operating temperature, accelerating drift in high temperature environments.
Material selection and low-stress single crystal silicon construction minimize long term physical deformation.
Elevated Drift
Shifts in resting proof mass position change nominal sensing capacitance values under zero input acceleration. Zero point drift invalidates factory offset calibration, introducing continuous bias errors into inertial navigation calculations. Sensor systems require periodic field recalibration to compensate for creep induced bias changes.
Structural design limits peak operating stresses on flexure beams to suppress material creep rates.
Drift Boundary
Long term stability testing monitors sensor zero output drift under continuous high temperature storage. Metrology protocols measure offset variations over thousand-hour exposure periods to quantify creep rates. Compliance standards enforce maximum allowable bias drift limits to guarantee navigation accuracy over operational lifespans.
