Sensitivity Stability
Metrological performance of piezoresistive strain sensors depends on the constancy of the transducer conversion ratio over time. Gauge factor drift is the gradual and unwanted change in the sensitivity coefficient of a strain gauge during operation. This instability is distinct from zero-point offset drift because it scales proportionally with the applied strain.
Temperature Dependency
Thermal and environmental stress are primary drivers of the drift. Long-term exposure to elevated temperatures can cause atomic realignment and dopant redistribution within the piezoresistive element, altering its gauge factor. The rate of gauge factor drift often increases exponentially with temperature, following an Arrhenius relationship.
Material choice influences this rate, with metallic foil gauges exhibiting much lower drift than semiconductor-based sensors.
Calibration Shift
Measurement uncertainty increases when the sensitivity of the sensor changes without a corresponding correction factor. The drift introduces a systematic scaling error into the measured strain values. In high-precision applications, the gauge factor drift must be characterized through periodic recalibration or simulated using finite element models.
Compensation Strategy
Minimizing the drift relies on material stabilization and circuit-level adjustments. Advanced manufacturing processes include high-temperature burn-in cycles to stabilize the microstructure before the sensor is deployed. Compensation circuits can also be used to adjust the excitation voltage or gain of the amplifier to counter the drift.
