Piezocomposite 30MHz linear array for medical imaging: design challenges and performances evaluation of a 128 elements array

The range of applications demanding the development of high frequency ultrasound imaging is very broad, from dermatology and ophthalmology to intravascular and small animals imaging, to improve the resolution of the images over a small penetration depth. However the manufacture of such imaging systems remains very challenging from both transducer manufacture (small dimensions of the elements, thin layers materials properties control) and associated electronic system perspectives. This article extends the current state of the art limited at 20 MHz for fully operational array devices and presents the acoustical design, manufacture and evaluation of a 128 elements 30 MHz ultrasound array based on the 1-3 piezocomposite technology, with a 100 μm pitch and a 2 mm elevation aperture. Electro-acoustical characterisation of the full array is reported (in terms of bandwidth, pulse duration and homogeneity performance) as well as electrical characterisation (impedance and cross-coupling measurements).