Characterization of a parametric resonance based capacitive ultrasonic transducer in air for acoustic power transfer and sensing

Capacitive transducers typically require a DC bias or a pre-charged electret to operate, rendering them non-ideal for applications such as energy harvesting and wireless power transfer. Parametric resonance based capacitive transducers offer an alternative to traditional capacitive transducers as they can be operated without the need for a bias voltage or a pre-charged electret In this paper, we experimentally validate a 1D lumped parameter model and characterize a CPUT operating in air at 50 kHz for ultrasonic power transfer and sensing applications. This particular CPUT is able to recover 40.5 mu W of power at an efficiency of 0.32% without any DC bias when excited by a 50 kHz piezoelectric transducer. The application of the CPUT as a highly sensitive acoustic sensor is explored by making use of active electrical circuits that reduce the resistance of the system. Finally, the capability of the CPUT as a highly directional acoustic sensor is presented with the electrostatic transducer demonstrating a directivity of +/- 1 degrees when operated as a CPUT as compared to +/- 13 degrees when operated as a conventional biased receiver. These results set the stage for the application of CPUT as a multi-functional acoustic transducer. (C) 2020 Elsevier B.V. All rights reserved.

电容式换能器通常需要直流偏置或预充电驻极体才能工作，这使得它们在能量收集和无线电力传输等应用中不太理想。基于参量共振的电容式换能器为传统电容式换能器提供了一种替代方案，因为它们无需偏置电压或预充电驻极体即可工作。在本文中，我们通过实验验证了一个一维集总参数模型，并对一个在空气中以50 kHz频率工作的电容式参量超声换能器（CPUT）进行了特性分析，以用于超声功率传输和传感应用。当由一个50 kHz的压电换能器激励时，这个特定的CPUT在没有任何直流偏置的情况下能够以0.32%的效率回收40.5微瓦的功率。通过利用有源电路降低系统电阻，探索了CPUT作为一种高灵敏度声学传感器的应用。最后，展示了CPUT作为一种高指向性声学传感器的能力，静电换能器作为CPUT工作时表现出±1度的指向性，而作为传统的偏置接收器工作时指向性为±13度。这些结果为CPUT作为一种多功能声学换能器的应用奠定了基础。（C）2020爱思唯尔有限公司。保留所有权利。