The focus of this project is to model and control piezoelectric thin-film actuators for miniature imaging instruments. Certain high-resolution imaging techniques can penetrate relatively deeply into biological tissue. Use of this ability with living organisms through small handheld and/or endoscopic tools requires precise control of novel micro-scale actuators, such as those based on the piezoelectric material lead-zirconate-titanate (PZT), deposited as thin-film on silicon wafers. Compact mathematical models will be developed to describe thin-film PZT behavior at varying operating frequencies and amplitudes. This will be incorporated into dynamic models of actuator structural motion subject to variation in actuator manufacturing, and techniques from the field of robust control will be used to design actuators that are comparatively insensitive to fabrication errors and piezoelectric material variability. Finally, feedback controllers based on the preceding models will be designed to regulate actuator motion using on-board sensing measurements.
The proposed work will have broad impact by supporting miniaturization of deep-tissue optical microscopy systems to an endoscope-compatible form factor. These instruments would enable a variety of scientific and clinical activities regarding topics such as systems biology, cancer, and allergic disease. Better understanding of thin-film PZT behavior could also improve a variety of micro-scale actuators based on piezoelectric materials, such as nanopositioners, micro-robots, and optical scanning mirrors. Design for robustness could help reduce susceptibility of microtechnologies to poor yield or limited performance due to processing and environmental variability. Educationally, undergraduate researchers will be heavily involved in experimental testing of prototype devices and control system implementation, through engineering internship programs targeting women and underrepresented minorities. Support would also be used to develop and implement engineering design and experimentation activities in the University of Michigan Detroit Area Pre-College Engineering Program.