Thermogravitational microcolumn for thermodiffusion study of biological fluids


A. Martin1, M. Klein2, M. Bou-Ali1 and S. Wiegand2

1Mondragon Goi Eskola Politeknikoa, Spain
2Institut für Festkörperforschung, Forschungszentrum Jülich, Germany

Keywords: thermodiffusion, thermogravitational column, colloids
property: thermodiffusion coefficient
material: biological fluids

Separation processes related to the thermodiffusion effect have been of great interest in the scientific community for a large number of fields where they play an important role [1]. Due to the increased sensitivity and the possibility to generate more accurate results in new methods, the thermodiffusion is now also studied in complex fluids, i.e colloids. The thermodynamic effect has been presented as a possible mechanism for biological transport [2], mass transport in living beings [3] and there are even studies suggesting that the thermodiffusive effect could improve the ability to influence biological systems[4]. Until now, several non-convective microdevices have been presented for studying thermodiffusion effect in colloidal systems [ 3, 5].

In this paper, a new thermogravitational column design adapted to an optical measuring system is presented to study the thermodiffusion in synthetic and biological dispersions. This microdevice is considered ideal for this type of systems due to the low sample volume needed and due to fairly low relaxation times. In addition, it is designed, particularly in respect to the aspect ratio used for the internal cavity, to be within the limits of validity of the FJO theory. This allows the determination of the thermodiffusion coefficient DT from stationary separation measures, as well as measurements of the separation degree of the analyzed fluid. In particular, this paper presents both the design and the numerical validation of the thermogravitational microcolumn.

References
  1. Bou-Ali M.M., Platten J.K., Thermodiffusion: Basics and Applications, Mondragon Unibertsitateko Zerbitzu Editoriola (2006).

  2. Bonner F.J., Sundelof L.O., Z. Naturforsch C. 39, 656 (1984)

  3. D. Braun and A. Libchaber, Physical Biology, 1, (2004).

  4. R.D. Astumian, Proceedings of the National Academy of Sciences, 104, p. 3 (2007)

  5. M. Hartumg and W. Köhler; M. M. Bou-Ali y J. K. Platten, Eds, Mondragón Unibertsitatea Press, Spain, p. 113, (2006)

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