A Planar Fabricated 1-3 Composite Ultrasonic Transducer to Determine the Dynamic Response of Microstructures

A novel excitation device using pulsed 1–3 composite ultrasonic transducer is presented. This composite transducer generates a bulk acoustic wave (BAW) to impact the microstructures like a hammer. Thus, a broad bandwidth and constant power spectrum for the vibration test of microstructures are available. The characteristics of a BAW hammer produced with the 1–3 composite transducer were simulated by commercial software PIEZOCAD. According to the proposed wafer level fabrication process of the 1–3 composite BAW hammer, it is possible to design the 1–3 composite BAW hammer to generate an impulse with a specific waveform. Thus the natural behavior of the microstructure within a specific frequency range can be determined. The experimental results of a BAW hammer with composite structure agree well with the simulation predictions. Moreover, the dynamic response of microstructures including the resonant frequency, mode shape and the modal damping can be measured in a single impulse excitation. Since the measurement apparatus is readily to be built, this approach has the potential to do the on-line test for batch production.