Inversion-Based Nanopositioning Control For Ultra-high-speed Scanning Probe Microscopy

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In this GOALI project, a suite of novel control techniques based on the system-inversion theory will be developed to significantly increase the operation speed of scanning probe microscope (SPM) with large imaging size and large sample asperities. To achieve high-speed precision positioning during lateral scanning, an inversion-based iterative control (IIC) algorithm will be studied to simultaneously compensate-for the nonlinear hysteresis and the vibrational dynamics effects of piezo actuators. A cascade model consisting of the Preisach-based hysteresis model followed by the linear dynamics will be explored to investigate the convergence of the IIC algorithm. To achieve precision positioning of the AFM-probe in the vertical-axis, a novel two degree-of-freedom feedforward-feedback controller will be developed to enable the inversion-based feedforward controller and the robust feedback controller to work in concert. Furthermore, an optimal output transition technique that reduces output oscillations by minimizing the output-energy will be integrated with the IIC algorithm to achieve high-speed adhesion force measurement. The developed control techniques will be implemented and evaluated in a set of scientific and engineering studies, through the collaborations with the PI's colleagues at ISU.Developing ultra-high-speed SPM resonates with the grand challenge areas of nanotechnology ("Nanoscale Instrumentation and Metrology") identified by the National Nanotechnology Initiative. Ultra-high-speed SPM will revolutionize the use of SPM in numerous areas, including, but not limited to, biomedical imaging (e.g., study of rapid biological processes such as living cell locomotion), analytical chemistry (e.g., real-time monitoring of single-molecule reactions), nanomanufacturing (high-throughput manufacturing of nanodevices for practical uses), and bioassays. The proposed education and outreach activities of the project will stimulate women/minority students' interests in science/engineering areas at their early age through the Open-Lab tours and mentoring freshman undergraduates. The collaboration with Veeco, the industrial partner in this GOALI project, will enhance the graduate students' industry experience through summer internships, and accelerate the transfer of the developed technology to the industry.