GHz Fingerprint Acoustic Imaging by Mechanically Scanning a Soft Conductive Probe on Epitaxial PbTiO3 Films

The high relative dielectric constant in epitaxial PbTiO
₃
thin film ultrasonic transducer is attractive for reducing acoustic source size and leads high spatial resolution in the 50 Ω measurement system. Because a large integrated transducer array on wafer is difficult to be fabricated many times it is desired to examine the quality of acoustic images, which piezoelectric transducer wafer will acquire. In this letter, by mechanically scanning a soft conductive probe as a top electrode on the surface of epitaxial PbTiO
₃
transducer wafer, GHz acoustic reflectance images were obtained in a finger print phantom.