A kind of micro piezoelectric composite ultrasonic detector with good directivity is designed and fabricat⁃ed based on microfabrication process. The detector includes a piezoelectric vibrator,a damper,a relay and ultra-high frequency(UHF)connector. A piezoelectric vibrator is composed of a 4 × 4 80μm × 80μm × 130μm(length × width × height)lead zirconate titanate(PZT)piezoelectric columnar array and the array gap filling an epoxy resin. When the piezoelectric vibrator is applied a high frequency AC voltage to the columnar PZT array,it produces longi⁃tudinal stretching movement,thereby generating ultrasonic radiation to the media. As the epoxy filler material,it can absorb the noise due to the columnar PZT array caused by vibrations in other directions so that the detector can produce a good directivity ultrasonic wave in the longitudinal direction,and improve the detection sensitivity. The test results show that the fabricated micro piezo detector has a good directivity,a high sensitivity,a high accuracy, and can be used in measuring the moisture content in the sediment.%基于微细加工工艺，设计并制备了一种指向性良好的压电复合材料的超声波探测器。该探测器由压电振子、阻尼器、中继板和特高频（UHF）连接器构成。压电振子由4×4个（80μm×80μm×130μm）（长×宽×高）的锆钛酸铅（PZT）压电柱状阵列及阵列缝隙填充环氧树脂而构成。当压电振子施加高频交流电压时，柱状PZT阵列产生纵向伸缩运动，从而产生超声波并向介质辐射。作为填充材料的环氧树脂，能够吸收掉因柱状PZT阵列其他方向振动而引起的噪声，使探测器在纵向上能产生指向性良好的超声波，从而提高了该探测器的灵敏度。测试结果表明，该微压电探测器指向性好，灵敏度高，精度高和抗干扰性好，可应用在泥沙的含水量测量中。
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