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Cylindrical ultrasound transducers for intravascular and endolumenal imaging applications

Conventional ultrasound imaging transducers are fabricated using planar geometries—of materials and in most subsequent processing (bonding, dicing, etc.); this can lead to complications in assembling catheter- or endoscope-based devices, and/or significant inherent limitations in their design and application. Miniature cylindrical transducer devices offer the potential for more straightforward design for 360-deg imaging applications, albeit with unique fabrication challenges. We have developed a novel technique for processing cylindrical ultrasound transducer geometries, and used it to fabricate prototype devices designed for intravascular and endolumenal applications. We created a custom dicing setup allowing a tube of radially poled piezoceramic (PZT-4) as small as 4.6 Fr (1.53 mm diameter) to be cut circumferentially, to a specified depth or completely through the wall of the tube, at precise axial locations. The resulting cylindrical transducer was connected to a function generator and power amplifier, and driven at 7.5 MHz to generate axisymmetric, radially directed acoustic radiation force impulse (ARFI) displacements up to 19 μm in a tissue-mimicking elasticity phantom. This demonstrates that miniature cylindrical transducers can be made to enable 360-deg elasticity imaging of the mechanical properties and structure of tissues, to identify vulnerable atherosclerotic plaques or quantify softening of the cervix prior to labor onset.Conventional ultrasound imaging transducers are fabricated using planar geometries—of materials and in most subsequent processing (bonding, dicing, etc.); this can lead to complications in assembling catheter- or endoscope-based devices, and/or significant inherent limitations in their design and application. Miniature cylindrical transducer devices offer the potential for more straightforward design for 360-deg imaging applications, albeit with unique fabrication challenges. We have developed a novel technique for processing cylindrical ultrasound transducer geometries, and used it to fabricate prototype devices designed for intravascular and endolumenal applications. We created a custom dicing setup allowing a tube of radially poled piezoceramic (PZT-4) as small as 4.6 Fr (1.53 mm diameter) to be cut circumferentially, to a specified depth or completely through the wall of the tube, at precise axial locations. The resulting cylindrical transducer was connected to a function generator and power amplifier...