  Lead Zirconate Titanate [(ZrxTi1-x)O3 ]is used to make ultrasound
transducers, sensors, and actuators due to its large piezoelectric coefficient.
Several surfaces and subsurface micro defects develop within the Lead Zirconate
Titanate (PZT) sensor due to delamination, corrosion, huge temperature
fluctuation, etc., causing a decline in its performance. It is thus necessary
to identify, locate, and quantify the defects. Non-Destructive Structural
Health Monitoring (SHM) is the most optimal and economical method of
evaluation. Traditional ultrasound SHM techniques have a huge impedance
mismatch between air and any solid material. And most of the popular signal
processing methods define time-series signals in only one domain which gives
sub-optimal results. Thus to improve the accuracy of detection point contact
excitation and detection methods have been implemented to determine the
interaction of ultrasonic waves with microscale defects in the PZT. And Haar
Discrete Wavelet Transformation (DWT) is applied to the time series data
obtained from the Coulomb coupling setup. Using the above process, defect up to
100 um in diameter could be successfully distinguished and localized.
