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首页> 外文期刊>IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control >Air-Coupled Ultrasonic Ferroelectret Receiver With Additional Bias Voltage
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Air-Coupled Ultrasonic Ferroelectret Receiver With Additional Bias Voltage

机译：具有附加偏置电压的空气耦合超声铁电驻极体接收器

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摘要

High sensitivity is an important requirement for air-coupled ultrasonic sensors applied to materials testing. With a lower acoustic impedance than any piezoelectric material, charged cellular polypropylene (PP) offers better matching to air with a similar piezoelectric coefficient. The piezoelectric properties of charged cellular PP originate from their polarization, creating permanent internal voltage. The sensitivity of the sensor can be increased by applying additional dc bias voltage, as it has been done already for transmitters. This work presents the first ultrasonic sensor based on charged cellular PP including a high-voltage module providing dc bias voltage up to 2 kV. This bias voltage led to an increase in the signal-to-noise ratio of up to 15 +/- 1 dB. The measurement of the received signal depending on the applied bias voltage is proposed as a new method of determining the internal voltage of ferroelectrets. The sensor combined with a cellular PP transmitter was applied to nondestructive testing of a rotor blade segment and glued-laminated timber, enabling imaging of the internal structure of these specimens with a thickness around 4 cm.
机译：高灵敏度是空气耦合超声传感器应用于材料测试的重要要求。具有比任何压电材料更低的声阻抗，带电多孔聚丙烯（PP）可更好地匹配具有类似压电系数的空气。带电的多孔PP的压电特性源自其极化，产生永久的内部电压。传感器的灵敏度可以通过施加额外的直流偏置电压来提高，这已经在变送器中完成了。这项工作提出了第一个基于带电蜂窝式PP的超声波传感器，包括一个提供高达2 kV直流偏置电压的高压模块。该偏置电压导致信噪比增加高达15 +/- 1 dB。作为确定铁电驻极体内部电压的新方法，提出了根据施加的偏置电压来测量接收信号的方法。该传感器与蜂窝式PP发射器相结合，用于转子叶片段和胶合层压木材的无损检测，能够对厚度约为4 cm的这些样品的内部结构进行成像。

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