Robert Cohn

Professor

Robert W. Cohn is Professor of Electrical and Computer Engineering, Director of the ElectroOptics Institute and Nanotechnology Center at the University of Louisville. He holds degrees in English and Electrical Engineering from the University of Kansas, and the PhD in Electrical Engineering from Southern Methodist University. Prior to joining UofL in 1989, as Member of the Technical Staff at Texas Instruments he studied system devices for signal processing, including precision-fabricated surface acoustic wave filters and deformable mirror devices that now are widely used in digital light projectors. His first studies at UofL centered on the development of video rate calculation and display of computer generated holograms. He studied applications of these real-time holograms both for multi-object laser targeting and for laser trapping microscopes. Since 1998 his research has increasingly focused on fabrication of high aspect ratio nanostructures and self-assembly, including of self-assembled freestanding metal alloy nanowires, which were the basis for the spin-off company NaugaNeedles, and self-assembled polymer nanostructures, for which Cohn received an NSF Nanotechnology Interdisciplinary Research and Technology (NIRT) award. Professor Cohn is Fellow of the Optical Society of America for his research on real-time computer holography and in 2000 he received the University of Louisville's President's Award for Scholarship, Research and Creative Activity. He has published over 60 refereed journal publications and 8 patents and has served as Principal Investigator on over 40 grants or contracts. In 2009 during his sabbatical year he studied properties of liquid and polymer wetting and capillarity with Prof. David Quéré at ESPCI Paris Tech in Paris, the institute made famous by de Gennes, Langevin and the Curies (Marie, Pierre, Frederic, Irene, Jacques).

Education

  • Ph.D. in Electrical Engineering, Southern Methodist University, 1988
  • M.S. in Electrical Engineering, University of Kansas, 1982
  • B.S. in Electrical Engineering, University of Kansas, 1978
  • B.A. in English Literature, University of Kansas, 1975

Publications

A Thermoacoustic Model for High Aspect Ratio Nanostructures- 2016

In this paper, we have developed a new thermoacoustic model for predicting the resonance frequency and quality factors of one-dimensional (1D) nanoresonators. Considering a nanoresonator as a fix-free Bernoulli-Euler cantilever, an analytical model has been developed to show the influence of material and geometrical properties of 1D nanoresonators on their mechanical response without any damping. Diameter and elastic modulus have a direct relationship and length has an inverse relationship on the strain energy and stress at the clamp end of the nanoresonator. A thermoacoustic multiphysics COMSOL model has been elaborated to simulate the frequency response of vibrating 1D nanoresonators in air. The results are an excellent match with experimental data from independently published literature reports, and the results of this model are consistent with the analytical model. Considering the air and thermal damping in the thermoacoustic model, the quality factor of a nanowire has been estimated and the results show that zinc oxide (ZnO) and silver-gallium (Ag2Ga) nanoresonators are potential candidates as nanoresonators, nanoactuators, and for scanning probe microscopy applications.

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