Baseline Shift
Output instability at the null point characterizes the gradual change in the bridge balance of a pressure sensor over time or temperature cycles. Such piezoresistive zero drift appears as an apparent pressure reading even when the actual applied pressure is zero.
Bridge Stability
Resistance changes in the sensing elements occur as the material experiences internal stress relaxation or atomic migration. During the evaluation of piezoresistive zero drift, the sensor is cycled through its full temperature range to identify the unrepeatable portion of the offset. This shift is often caused by the mismatch in expansion between the silicon diaphragm and the glass or metal header.
Compensation resistors or digital correction algorithms are applied to null the effect, but the long term stability depends on the quality of the initial bond. Monitoring the piezoresistive zero drift over several months allows the user to determine the recalibration interval needed to maintain accuracy. Stable readings confirm quality.
Signal Compensation
Digital controllers often subtract the measured offset from the raw signal to provide a corrected output to the system. If the piezoresistive zero drift is too large, the compensation logic may run out of range and trigger an error flag.
Measurement Error
Final accuracy specifications always include a component for the instability of the bridge at zero pressure. Excessive piezoresistive zero drift indicates that the sensor is nearing the end of its reliable service life.
