Electric Tweezers: Experimental Studies of Positive Dielectrophoresis-Based Positioning and Orientation of a Nanorod

The manipulation of individual micrometer sized objects has been the focus of significant research efforts over the last few years. A previously proposed method for the arbitrary manipulation of nanoparticles is experimentally demonstrated. This method employs dielectrophoretic forces for the planar control of the motion and orientation of such nanoparticles between a set of microfabricated electrodes. Each electrode is approximated as a set of sources, namely, an unknown point charge and induced dipole. Imposing constraints on the electric field at the location of the particle and requiring self-consistency uniquely determine the sources. They can then be subsequently used to determine the set of electrode voltages that creates an electric field that will produce the prescribed orientation and force on the particle. The drag coefficients of a nanorod are experimentally determined by sequentially applying a constant force both parallel and perpendicular to its axis and observing a resulting motion.With the drag coefficients in hand, the velocity rather than force can be prescribed, and the rod is directed to move accurately at oblique angles to its orientation. The rod is in a constant state of unstable equilibrium and requires negative feedback to maintain a fixed position. The automation of such feedback is demonstrated, allowing a controlled travel of the nanostructures over complex paths. Comments Copyright (2007) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. Reprinted in Journal of Applied Physics, Volume 102, Issue 2, Article 024913, July 15 2007, 5 pages. Publisher URL: http://dx.doi.org/10.1063/1.2753584 This journal article is available at ScholarlyCommons: http://repository.upenn.edu/ese_papers/284 Electric tweezers: Experimental study of positive dielectrophoresis-based positioning and orientation of a nanorod Brian Edwards and Nader Engheta Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 Stephane Evoy Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2E1, Canada and National Institute for Nanotechnology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada Received 29 January 2007; accepted 29 May 2007; published online 26 July 2007 The manipulation of individual micrometer sized objects has been the focus of significant research efforts over the last few years. A previously proposed method for the arbitrary manipulation of nanoparticles is experimentally demonstrated. This method employs dielectrophoretic forces for the planar control of the motion and orientation of such nanoparticles between a set of microfabricated electrodes. Each electrode is approximated as a set of sources, namely, an unknown point charge and induced dipole. Imposing constraints on the electric field at the location of the particle and requiring self-consistency uniquely determine the sources. They can then be subsequently used to determine the set of electrode voltages that creates an electric field that will produce the prescribed orientation and force on the particle. The drag coefficients of a nanorod are experimentally determined by sequentially applying a constant force both parallel and perpendicular to its axis and observing a resulting motion. With the drag coefficients in hand, the velocity rather than force can be prescribed, and the rod is directed to move accurately at oblique angles to its orientation. The rod is in a constant state of unstable equilibrium and requires negative feedback to maintain a fixed position. The automation of such feedback is demonstrated, allowing a controlled travel of the nanostructures over complex paths. © 2007 American Institute of Physics. DOI: 10.1063/1.2753584