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AC Electrokinetics: applications for nanotechnology

Michael Pycraft Hughes*

European Institute of Health and Medical Sciences/School of Mechanical and Materials Engineering,
University of Surrey Guildford, Surrey, GU2 5XH, United Kingdom

This is an abstract for a presentation given at the
Seventh Foresight Conference on Molecular Nanotechnology.
The full article is available at


AC Electrokinetic techniques such as dielectrophoresis [1,2] and electrorotation [3] have been utilised for many years for the manipulation, separation and analysis of cellular-scale particles. The phenomenon occurs due to the interaction of induced dipoles with dynamic electric fields, and can be used to exhibit a variety of motions including attraction, repulsion and rotation by changing the nature of the dynamic field.

Recent advances in semiconductor manufacturing technology have enabled researchers to develop electrodes for manipulating macromolecules as small as 9kDa using both attractive [4] and repulsive [5] AC electrostatic forces, and to concentrate 14nm beads from solution [6]. Trapping of single particles such as viruses and 93nm-diameter latex spheres in contactless potential energy wells [7] has also been demonstrated. AC Electrokinetics offers advantages over scanning-probe methods of nanoparticle manipulation in that the equipment used is simple, cheap and has no moving parts, relying entirely on the electrostatic interactions between the particle and dynamic electric field. Furthermore, there is theoretical evidence that as manufacturing technology further improves, single particles considerably smaller than presently studied using AC Electrokinetics may be manipulated.

Ultimately, such a technology will have obvious applications for the manipulation of single molecules. Previous studies [4,7] have shown that the trapping efficiency of planar electrode arrays is dependent on a number of factors including the magnitude and dimensions of the electric field and the radius of the particle to be trapped. In this paper we will consider the ways in which AC Electrokinetics can benefit nanotechnology, and the constraints on the technique due to factors such as Brownian motion, heating of the medium, and electrode dimensions as the electrode array is miniaturised to the nanometre scale.

  1. Pohl, HA 1978 "Dielectrophoresis" Cambridge: Cambridge University Press
  2. Jones, TB 1995 "Electromechanics of Particles" Cambridge: Cambridge University Press
  3. Zimmermann U, Neil GA 1996 "Electromanipulation of Cells" New York: CRC Press
  4. Washizu M, Suzuki S, Kurosawa O, Nishizaka T and Shinohara T 1994 IEEE Trans. Ind. Appl; vol. 30 pp 835-43
  5. Bakewell DJG, Hughes MP, Milner JJ and Morgan H 1998 Proc. 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Publications)
  6. Muller T, Gerardino A, Schnelle T, Shirley SG, Bordoni F, De Gasperis G, Leoni R and Fuhr G 1996 J. Phys. D: Appl. Phys; vol. 29 pp.340-349
  7. Hughes MP and Morgan H 1998 J. Phys. D: Appl. Phys; vol. 31 pp. 2205-2210

*Corresponding Address:
Michael Pycraft Hughes
European Institute of Health and Medical Sciences/School of Mechanical and Materials Engineering,
University of Surrey Guildford, Surrey, GU2 5XH, United Kingdom
Tel: +44 1483 300800; Fax: +44 1483 306039


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