Abstract

PMN-PT is one of promising materials for fabrication ultrasound sensors for flow metering, in that the relative permittivity and the dielectric loss factor are superior to PZT, the popular piezoelectric materials at present. However, there are not many studies focusing on characterizing the PMN-PT ultrasound sensors by acoustic measurements. This study introduces an acoustic bath to accommodate a pair of ultrasound sensors for measuring the relative acoustic sensitivity and the dispersion angle by ultrasound waves.

Ultrasound sensors with resonance frequencies from 0.2 MHz to 1 MHz are also tested in terms of the relative permittivity, the dielectric loss factor, the electric impedance, and the electric admittance. From these measurements, it is found that PMN-PT is superior to PZT for increasing the relative acoustic sensitivity of ultrasound sensors. Impedance matching electronic circuits are fabricated by designing capacitance and inductance with the reflectance coefficients. Smith chart is used to calculate the capacitance and the inductance for the PMN-PT ultrasound sensors with resonance frequencies of 0.2 MHz and 0.5 MHz. As a results, it is also found that the impedance matching electronic circuits enhance the electrical admittance by 3.6 ∼ 25 times while keeping the electrical impedance between 50 Ω and 100 Ω.

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