RUI: Excitation of Macro and Micro Cantilevers Using Ultrasound Radiation Force

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The goal of this faculty-student project is a comprehensive study of excitation of vibrational modes of macro and micro cantilevers using the ultrasound radiation force. The ultrasound radiation force excitation method is a non-contact technique that relies on the interference between two or more ultrasound frequencies incident on an object. This interference produces a radiation force at the difference frequency, which can induce vibrations in the object. The ultrasound radiation force will be used to vibrate cantilevers spanning over two orders of magnitude in size and with resonance frequencies from less than 100 Hz to over 200 kHz. Of particular interest will be the study of a method whereby a pair of ultrasound transducers can selectively excite different vibrational modes, depending on whether the transducers are driven with the same phase or differing phases. A computational model of the ultrasound excitation process will be developed, both to better understand the underlying excitation mechanism, and also to facilitate future research. This project will result in a more fundamental understanding of the capabilities of ultrasound radiation force for noncontact excitation of macro and microcantilevers and similar objects.This project will have a broad impact, because of the important role that the vibration of microcantilevers plays in an ever increasing number of applications. By monitoring changes in the vibrational state of a microcantilever, it is possible to detect the minute change in mass when single cells, viruses or certain molecules attach to the microcantilever. Similarly, in the realm of materials science, researchers routinely use atomic force microscopy to study surfaces. These important techniques may benefit from the noncontact nature of the ultrasound radiation force. The capability of selective excitation of microcantilevers may enhance the sensitivity of these techniques as compared with conventional excitation methods.The undergraduate students involved in this project will get the extraordinary opportunity to perform cutting-edge on-campus research and also collaborate with well-known research groups at other institutions. The students will gain experience in a wide range of fields, including acoustics, optics, computer-controlled data acquisition, signal processing, modal analysis and computer modeling; this is valuable training for careers in either physics or engineering. They will also develop demonstrations to better communicate this research area to the public and to enhance Gustavus' well-established K-12 outreach programs.