Explain why calibration drift happens and how to mitigate it in practice.

• A. It happens randomly with no cause; mitigation is impossible.
• B. It only happens in new sensors; ignore.
• C. It can be prevented by ignoring calibration.
• D. Sensor aging, environmental conditions, and electronics degradation; mitigate with regular calibration, zero checks, and component replacement.

Answer: (A)

Calibration drift occurs because a sensor’s response changes over time due to multiple real-world factors. The sensing element itself can age, altering its sensitivity or baseline. Environmental conditions such as temperature, humidity, pressure, and exposure to chemicals can push the sensor away from its initial calibration. The electronics that condition and read the signal—reference voltages, amplifiers, and ADCs—can also drift, shifting offset and gain. Other contributors include fouling or contamination of the sensing surface, mechanical wear, and changes in wiring or power supply stability. All of these factors can cause the output to slowly move away from the true value, even if the measured quantity hasn’t changed.

Mitigation centers on a practical calibration routine and good maintenance. Regular calibration against traceable standards helps catch drift before it matters. Performing zero checks (offset) and span checks (gain) periodically reveals how much drift has occurred and in what direction. Replacing aging components or faulty electronics when drift exceeds acceptable limits keeps the system accurate. Additional measures—environmental controls, temperature compensation, sensor cleaning or fouling prevention, and redundant sensing or sensor fusion—reduce the rate of drift and improve reliability. In short, treat calibration as an ongoing quality control process rather than a one-time fix.