W. H. Liew, K. Yao, S. Chen and F. E. H. Tay, "Piezoelectric Nanotube Array for Broadband High-Frequency Ultrasonic Transducer," in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 65, no. 3, pp. 457-464, March 2018.
Abstract:
Piezoelectric materials are vital in determining ultrasonic transducer and imaging performance as they offer the function for conversion between mechanical and electrical energy. Ultrasonic transducers with high frequency operation suffer from performance degradation and fabrication difficulty of the demanded piezoelectric materials. Hence, we propose one-dimensional (1D) polymeric piezoelectric nanostructures with controlled nanoscale features to overcome the technical limitations of high frequency ultrasonic transducers. For the first time, we demonstrate the integration of well-aligned piezoelectric nanotube array to produce high frequency ultrasonic transducer with outstanding performance. We find that nanoconfinement induced polarization orientation and unique nanotube structure lead to significantly improved piezoelectric and ultrasonic transducing performance over the conventional piezoelectric thin film. A large bandwidth 126 % (-6 db) is achieved at high center frequency, 108 MHz. Transmission sensitivity of nanotube array is found 46 % higher than monolithic thin film transducer attributed to the improved electromechanical coupling effectiveness and impedance match. We further demonstrate high-resolution scanning ultrasonic imaging and photoacoustic imaging using the obtained nanotube array transducers, which is valuable for biomedical imaging application in the future.
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Funding Info:
This project is partially supported by Institute of Materials Research and Engineering (IMRE) A*STAR (Agency for Science, Technology and Research), and by Singapore Maritime Institute under the Asset Integrity & Risk Management (AIM) R&D Programme, Project ID: SMI-2015-OF-01, and IMRE/15-9P1115.