Development of large aperture, high-frequency piezo-electric transducers for photoacoustic imaging

In the recent years, SONAXIS has developed lens-focused ultrasound transducers (LFUTs) with central frequencies greater than 10MHz, and -6dB relative bandwidth larger than 120%. For instance the use of one of these transducers - 78MHz central frequency, 128% relative bandwidth, f/D≈1 - has been reported for biomedical imaging applications [Soliman et al., 2015]. Drawbacks of LFUTs include the attenuation of high-frequency (HF) acoustic waves by the lens material as well as reflexions in the lens. Lensless, self-focused ultrasound transducers (SFUTs) have been proposed as an alternative to LFUTs and have been reported to provide reduced insertion loss compared to the latter [Cannata et al., 2000]. Adequate design of piezocomposite materials (PCMs) make them suitable candidates for biomedical applications, since they can meet requirements in terms of electromechanical coupling coefficient, acoustical impedance, dielectric constant as well as dielectric and mechanical losses [Smith and Auld, 1991]. This study aims at the development and evaluation of SFUTs based on 1-3 PCMs for biomedical applications, as an alternative to LFUTs, with broad bandwidth and high central frequency.