Piezo-composite transducers have been widely used for medical applications such as the medical imaging, brain stimulator, blood flowmeter and humidity sensor due to its merits of high sensitivity and broad bandwidth. Conventional ultrasonic transducers and arrays were mostly developed with a rigid flat or curved front with a fixed curvature. However, most parts of the human body would have curved or irregular shapes such as a human skull or chest. Thus, a flexible ultrasound transducer may be preferred in the medical diagnosis devices. Recently, the flexible sensors or transducers are of great interest and the associated progress has been made for the medical imaging. However, published works have not provided an appropriate solution to overcome the limitations of metal-type electrodes such as cracking or delamination at the presence of transducer surface bending.
In this work, we have developed a flexible piezo-composite transducer composed of the active piezoelectric material (PZT-5H) and passive polymer matrix (PDMS) to achieve sufficient flexibility, sensitivity, and bandwidth for the medical applications. In addition, the flexible electrodes composed of silver nanowires (AgNWs) and PDMS were deposited on the transducer using the spray coating method. AgNW/PDMS electrode is a promising alternative to metal-type electrodes such as Au to possess a reliable durability to the cracks from the strained fatigue while providing a sufficient conductivity as an electrode.
The prototyped transducers can be applicable to the curved or irregular surface of the target structure for detecting any acoustic variation with high sensitivity and good matching contact.
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