Piezoelectric films have recently attracted considerable attention in the development of various sensor and actuator devices such as nonvolatile memories, tunable microwave circuits and ultrasound transducers. In this paper, an overview of the state of art in piezoelectric films for high frequency transducer applications is presented. Firstly, the basic principles of piezoelectric materials and design considerations for ultrasound transducers will be introduced. Following the review, the current status of the piezoelectric films and recent progress in the development of high frequency ultrasonic transducers will be discussed. Then details for preparation and structure of the materials derived from piezoelectric thick film technologies will be described. Both chemical and physical methods are included in the discussion, namely, the sol-gel approach, aerosol technology and hydrothermal method. The electric and piezoelectric properties of the piezoelectric films, which are very important for transducer applications, such as permittivity and electromechanical coupling factor, are also addressed. Finally, the recent developments in the high frequency transducers and arrays with piezoelectric ZnO and PZT thick film using MEMS technology are presented. In addition, current problems and further direction of the piezoelectric films for very high frequency ultrasound application (up to GHz) are also discussed.

中文翻译：

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用于生物医学应用中的高频超声换能器的压电薄膜

压电薄膜最近在各种传感器和致动器设备（例如非易失性存储器、可调微波电路和超声换能器）的开发中引起了相当大的关注。在本文中，概述了用于高频换能器应用的压电薄膜的最新技术。首先介绍压电材料的基本原理和超声换能器的设计注意事项。在回顾之后，将讨论压电薄膜的现状和高频超声换能器的最新进展。然后将描述源自压电厚膜技术的材料的制备和结构的细节。讨论中包括化学和物理方法，即溶胶-凝胶方法，气溶胶技术和水热法。压电薄膜的电和压电特性对换能器应用非常重要，例如介电常数和机电耦合因子，也得到了解决。最后，介绍了使用 MEMS 技术的具有压电 ZnO 和 PZT 厚膜的高频换能器和阵列的最新进展。此外，还讨论了用于甚高频超声应用（高达 GHz）的压电薄膜的当前问题和进一步方向。介绍了使用 MEMS 技术的具有压电 ZnO 和 PZT 厚膜的高频换能器和阵列的最新进展。此外，还讨论了用于甚高频超声应用（高达 GHz）的压电薄膜的当前问题和进一步方向。介绍了使用 MEMS 技术的具有压电 ZnO 和 PZT 厚膜的高频换能器和阵列的最新进展。此外，还讨论了用于甚高频超声应用（高达 GHz）的压电薄膜的当前问题和进一步方向。