Determining the in-plane and out-of-plane dynamic response of microstructures using pulsed dual-mode ultrasonic array transducers

A novel dual-directional actuation technique to determinate the in-plane and out-of-plane dynamic response of the microstructure is presented in this study. The dual-mode ultrasonic array transducer has been realized to simultaneously generate the in-plane and the out-of-plane pulsed bulk acoustic waves (BAW). Thus the array transducer can be exploited to excite the micromachined structures. This array transducer, which acts as a vibration exciter during the vibration test, is named the dual-mode BAW hammer. The performance of the dual-direction hammer was designed and simulated by the commercial finite element analysis software. In application of this technique, the micromachined cantilevers were employed to conduct the vibration test. Experimental results showed that the in-plane and the out-of-plane vibration modes of micro beams were simultaneously excited using the dual-mode BAW hammer. Since the sample and the measurement apparatus are very simple, this approach has the potential for wafer level on-line testing.