PMN-PT single crystal, high-frequency ultrasonic needle transducers for pulsed-wave Doppler application

Abstract

High-frequency needle ultrasound transducers with an aperture size of 0.4 mm were fabricated using lead magnesium niobate-lead titanate (PMN-33%PT) as the active piezoelectric material. The active element was bonded to a conductive silver particle matching layer and a conductive epoxy backing through direct contact curing. An outer matching layer of parylene was formed by vapor deposition. The active element was housed within a polyimide tube and a 20-gauge needle housing. The magnitude and phase of the electrical impedance of the transducer were 47 Ω and ;38 , respectively. The measured center frequency and ;6 dB fractional bandwidth of the PMN-PT needle transducer were 44 MHz and 45%, respectively. The two-way insertion loss was approximately 15 dB. In vivo high-frequency, pulsed-wave Doppler patterns of blood flow in the posterior portion and in vitro ultrasonic backscatter microscope (UBM) images of the rabbit eye were obtained with the 44-MHz needle transducer.

A 2.5-mm outer diameter photoacoustic endoscopic mini-probe based on a highly sensitive PMN-PT ultrasonic transducer

“…3(d)] coordinates systems, respectively. Although the new PMN-PT transducer's insertion loss was higher than typical values 26,27 , it showed an adequate PA signal sensitivity for colon vasculature imaging with a laser energy of ~0.04 mJ/pulse, which yielded an optical fluence of ~2.3 mJ/cm 2 (~12% of the ANSI safety limit for allowable skin laser fluence).…”

Label-free optical-resolution photoacoustic endomicroscopy in vivo

“…Although this value is lower than the damage threshold for general tissue (200 mJ/cm 2 ) [62], it is not be desirable for internal organ imaging, especially for clinical applications. We expect that the SNR of OR-PAEM can be significantly increased by employing more sensitive ultrasound detectors, such as a lead magnesium niobate-lead titanate (PMN-PT)-based US transducer [63] or an optical ultrasound detector [64,65]. An additional important task is to embody a multi-wavelength OR-PAEM system for visualizing various functional information, such as the oxygen saturation of hemoglobin, or molecular information, such as the distribution of various contrast agents or molecular probes [17-35, 39, 40].…”

A highly compact packaging concept for ultrasound transducer arrays embedded in neurosurgical needles

“…The physical proximity helps to overcome the limitation of imaging at shallow depth. Although previous work has demonstrated the successful integration of single-element ultrasound transducers into needles (Lockwood et al 1993;Schoenhagen 2002;Zhou et al 2007;Yuan and Jiang 2008;Paeng et al 2009;Irie et al 2012), devices of this type require mechanical translation or rotation of the transducer in order to construct planar images. Array transducers, conversely, enable the generation of 2D images by electronic steering, where the electronic driving system excites different transducer elements in order to direct and focus the ultrasound beam.…”