High-Performance Ultrasound Needle Transducer Based on Modified PMN-PT Ceramic With Ultrahigh Clamped Dielectric Permittivity

A modified Pb(Mg
_1/3
Nb
_2/3
)O
₃
-PbTiO
₃
(PMN-PT) polycrystalline ceramic with ultrahigh relative clamped dielectric permittivity (ε
^S
/ε
₀
= 3500) and high piezoelectric properties (d
₃₃
= 1200 pC/N, k
_t
= 0.55) was used to fabricate high-frequency miniature ultrasound transducers. A 39-MHz high-frequency ultrasound needle transducer with a miniature aperture of 0.4 mm × 0.4 mm was designed and successfully characterized. The fabricated needle transducer had an electromechanical coupling factor k
_t
of 0.55, large bandwidth of 80% at -6 dB, and low insertion loss of -13 dB. A wire phantom and porcine eyeball imaging study showed good imaging capability of this needle transducer. The transducer performance was found to be superior to that of other needle transducers with miniature apertures, making this modified PMN-PT ceramic-based needle transducer quite promising for minimally invasive procedures in medical applications.