Control of Atomic Force Microscope Micro-cantilever Dynamics: Mechatronics at the Nanoscale
Speaker:Prof. Reza Moheimani
Professor
University of Newcastle, Australia
Date & Time:28 Mar 2014 (Friday) 15:30 - 16:30
Venue:RLG108
Organized by:Department of Electromechanical Engineering

Abstract

The atomic force microscope (AFM) has emerged as a key enabling tool for nanoscience and nanotechnology providing scientists and engineers with one of the most versatile methods of imaging structures at nanometer-scale. The ability to operate in air and in fluid environments gives the AFM a significant advantage over competing microscopy methods such as the Transmission Electron Microscope and the Scanning Electron Microscope that must operate in vacuum. The AFM has brought about significant progress in numerous scientific fields ranging from nanotechnology through to life sciences and medicine. Being a “mechanical microscope", it has also been used to manipulate matter at the nanometer-scale. Thus, it has emerged as the driving technology in nanomanipulation and nanoassembly, and as the key tool in nanorobotics research.

A widely used AFM mode of operation is the tapping mode, in which the micro-cantilever is oscillated at its resonance frequency and comes into contact with the sample for a brief moment in each cycle. The quality (Q) factor of the AFM micro-cantilever influences both the maximum scan speed and the image quality when operating in tapping mode. In this talk, we present several new approaches to Q-factor control in AFM micro-cantilevers and explain how the Q factor can be changed as needed. One method is based on the idea of piezoelectric shunt control, whereby the mechanical damping of a piezoelectric self-actuating micro-cantilever is controlled by applying an electrical impedance to the piezoelectric transducer. Another method is based on using a feedback controller with strictly negative imaginary transfer function, which is known to result in a remarkably robust feedback loop due to the collocated nature of the micro-cantilever transfer function.

Biography

Reza Moheimani received his undergraduate degree in electrical engineering from Shiraz University in 1991 and completed his doctoral studies at The University of New South Wales, Australia in 1996. In 1997 he joined University of Newcastle, Australia, embarking on a new research program addressing the dynamics and control design issues related to high-precision mechatronic systems. Professor Moheimani is the founder and director of Laboratory for Dynamics and Control of Nanosystems, a multimillion-dollar state-of-the-art research facility. His current research interests are mainly in the area of ultrahigh-precision mechatronic systems, with particular emphasis on dynamics and control at the nanometer scale, including applications of control and estimation in nanopositioning systems for high-speed scanning probe microscopy, modeling and control of microcantilever-based devices, control of microactuators in microelectromechanical systems, and design, modelling and control of micromachined nanopositioners for on-chip atomic force microscopy.

His work has been recognised by a number of awards including the IFAC Nathaniel B. Nichols Medal (2014); IFAC Mechatronic Systems Award (2013); IEEE Control Systems Technology Award (2009); Australian Research Council Future Fellowship (2009); IEEE Transactions on Control Systems Technology Outstanding Paper Award (2007); Australian Research Council Postdoctoral Fellowship (1999); and several best student paper awards in various conferences. He has served on the editorial boards of a number of journals, including the IEEE/ASME TRANSACTIONS ON MECHATRONICS, IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, and Control Engineering Practice. He has chaired several international conferences and workshops and currently chairs the IFAC Technical Committee on Mechatronic Systems. He has published over 300 refereed papers and five books. He is a Fellow of IEEE, IFAC and Institute of Physics (UK).