The wafer is a piezoelectric resonator, expanding and contracting in response to electrical voltages at a precise, extremely high frequency.
该晶片是一个压电谐振器，以精准而极高的频率对电压作出反馈，进行放大和收缩。
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It does this by fitting small piezoelectric acoustic sensors to parts of the structure to detect the particular frequency of noise caused by a crack in aircraft-grade aluminium.
Transducers are made from arrays of tiny piezoelectric structures that convert electrical signals into ultrasound waves by vibrating at an appropriate frequency.