PZN-PT based smart probe for high temperature fluid viscosity measurements

A smart sensing system is proposed for high-temperature (up to 90 °C) viscosity measurement of viscous fluids. The proposed sensing system is based on a smart cantilever probe on which a new generation of piezoelectric materials, relaxor ferroelectric Pb(Zn(1/3)Nb(2/3))O(3−x)PbTiO(3) (PZN-PT), is bonded. The proposed system utilizes a PZN-PT single crystal for actuation and a laser displacement sensor for vibration detection. By analyzing the vibrational properties of the cantilever probe, the viscosity of measured fluids at different temperatures (up to 90 °C) were extracted. Lab tests were carried out to verify and evaluate the effect of this system on high-temperature measurements. Results show a consistent agreement with theoretical analysis. In comparison to the existing high-performance piezoelectric material, lead magnesium niobate-lead titanate solid solution (1−x)[Pb(Mg1/3Nb2/3)O3]−x[PbTiO3] (PMN-PT), PZN-PT has a steady performance at high temperatures and shows more reliability. The proposed sensing system can be applied to real-time monitoring of viscous fluids in high-temperature environments, such as vehicle cooling systems, power plant cooling tower fluid monitoring, and other heat transfer systems.