Submitted for “Identification of Existing and Emerging Microelectromechanical Systems (MEMS) Applications” session, sponsored by committee A2F09 Design and Testing of a MEMS Ultrasonic Transducer for Flaw Detection

Ultrasonic pulse-echo methods are versatile, effective procedures for inspecting welds in steel structures. However, the ultrasonic methods conventionally used have two disadvantages: inspection must be performed manually by a skilled technician, and the signal obtained at the time of one inspection provides no “memory” to be used at the time of a later inspection. Our research involves the development of MEMS ultrasonic flaw detection devices that could be permanently installed at critical locations, that would maintain a history of earlier signal characteristics, and that would be polled remotely. One purpose of this paper is to acquaint researchers with the development of MEMS devices, and another is to present experimental results demonstrating the feasibility of our approach for MEMS ultrasonic flaw detection in solids. We first outline the fabrication choices afforded to developers of such devices, and then describe the design decisions made in developing our device. We next describe results of electrical characterization, again using our chip and our experimental study of its electromechanical properties as a case study. We then describe the experiments we performed to establish chip performance as a detector of ultrasonic signals, with particular interest in its performance as a phased array transducer to localize a signal source. We report successful demonstration of signal detection and source localization, and conclude that a MEMS ultrasonic transducer can perform phased array signal detection in contact with solids.