20-MHz phased array ultrasound transducer for in vivo ultrasound imaging of small animals

•This is the first work to use relaxor ferroelectric PMN-0.28PT single crystal to make a 128-element 20-MHz phased-array ultrasound transducer with ability to in vivo imaging small animal organs. Optimized performance of ∼ 84 % average bandwidth at −6 dB and insertion loss of −43 dB are achieved. The axial and lateral resolutions of the transducer are determined to be 81 µm and 243 µm, respectively.•With this transducer and Verasonics image platform, in situ images of a fisheye images are acquired, demonstrating successful application of our developed high-frequency phased array transducer for biomedical research on small animals.•It is the first time that we used our developed very high acoustic impedance and very low attenuation matching material for high-frequency phase array transducer fabrication. The attenuation of the matching layer developed by this method is only 10 dB/mm at 40 MHz, superior than all reported matching materials, and therefore, enhance the performance of the ultrasound transducers. In vivo ultrasound imaging with phased array transducers is of great importance for both clinical application and biomedical research. In this work, relaxor ferroelectric PMN-0.28PT single crystal with very high piezoelectric constant d33 ≥ 2000 pC/N and electromechanical coupling coefficient k33 ∼ 0.92 is used to fabricate high-frequency phased array transducers. A 128-element 20-MHz phased array transducer is successfully fabricated, and the optimized performance of −6 dB average bandwidth of ∼ 84 % and insertion loss of −43 dB are achieved. The axial and lateral imaging resolutions of the transducer are determined to be 81 µm and 243 µm, respectively. With Verasonics image platform, in vivo fisheye images are acquired, demonstrating the potential application of our developed high-frequency phased array transducer for biomedical research on small animals.