Variable Curvature Flexible Transducer for Abdominal Expandable Imaging.

Expanding the imaging field of view (FOV) of medical ultrasound transducers will more effectively detect pathological behaviors of tissues or organs. Conventional rigid transducers can be realized by increasing the number of array elements or the curvature; however, the imaging aperture is fixed by the original size and shape during the manufacturing process. This article presented a 128-element, 3-MHz flexible curvature abdominal array (FCAA) with the goal of dynamically expanding the FOV within a 120° range. The piezoelectric stack was divided into small pitches through a double-cut process, and two-component viscoelastic substrates (TCVSs) were filled between adjacent array elements to generate tensile and compressive stresses during decomposition deformation. A 3-D-printed push-pull device provides sufficient mechanical support, resulting in a conformal minimum curvature radius of 46 mm. The innovative rigid-flexible composite backing layer was used to balance mechanical flexibility and high bandwidth (BW) of -6 dB to 67.6%. The results showed that the axial and lateral resolutions of the commercial phantom line target are 0.35 and 0.77 mm, respectively, and the axial and lateral resolutions of FOV 120° are 0.36 and 1.02 mm, respectively. The imaging performance of FCAA was verified by B-model imaging of the kidneys, intestines, uterus, and bladder of volunteers with a different body mass index (BMI). In addition, the 5-mm renal artery phantom verified the Doppler imaging function of FCAA. All the results demonstrated that FCPA has great potential clinical value in abdominal ultrasound and gynecological examination.