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 μW 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° when operated as a CPUT as compared to ±13° when operated as a conventional biased receiver. These results set the stage for the application of CPUT as a multi-functional acoustic transducer.

电容式换能器通常需要直流偏置或预充电的驻极体才能工作，这使其不适用于能量收集和无线电力传输等应用。基于参量谐振的电容式换能器提供了传统电容式换能器的替代选择，因为它们无需偏置电压或预充电的驻极体即可运行。在本文中，我们通过实验验证了一维集总参数模型，并表征了在50 kHz的空气中运行的CPUT的超声功率传输和传感应用。当由50 kHz压电换能器激励时，这种特殊的CPUT能够以0.32％的效率恢复40.5μW的功率，而没有任何直流偏置。通过使用有源电子电路来降低系统的电阻，探索将CPUT用作高灵敏度声传感器。最后，通过静电换能器展示了CPUT作为高指向性声传感器的能力，证明了当作为CPUT操作时，方向性为±1°，而作为常规偏置接收器则为±13°。这些结果为将CPUT用作多功能声换能器奠定了基础。