Sensors in Proactive Maintenance – A Case of LTCC Pressure Sensors

Sensors are a vital component part of any process-controlled system. Even though designed to properly operate at required conditions within the whole lifetime, all sensors exhibit some level of drift with time. When selecting the sensors for implementation in a system proactive maintenance their ageing in specific operating conditions should be considered as an important issue. Here we focus on thick-film piezoresistive sensors based on low temperature cofired ceramic (LTCC) and discuss their ageing in different regimes of operations. Frequent overloading and particularly with limit overpressures can result in observable drifts and unacceptable scattering from the calibrated characteristics. For the sensors operating in the water the overloads are even more critical. Moreover, under the regime with frequent overloads, some non-critical, intrinsic defects in the sensing structure, which normally do not affect the characteristics and are non-detectable by the output tests in serial production may develop into critical defects that shorten the sensor lifetime