Plastic and nonmetallic article shaping or treating: processes – Formation of solid particulate material directly from molten...
Patent
1996-08-23
1999-09-07
Mullis, Jeffrey
Plastic and nonmetallic article shaping or treating: processes
Formation of solid particulate material directly from molten...
264 6, 264 10, 264 15, B01J 200
Patent
active
059483288
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to three-dimensional microelectrode arrangements and processes for shaping suspended particles (particles, phases) or droplets of a liquid in electric fields, preferably high frequency fields, and to solidify or consolidate them under field influence. The invention also relates to certain uses of the shaped particles.
2. Prior Art
Numerous separation techniques in chemistry, medicine or biotechnology are based on the streaming through packed volumes of small particles serving as filters or carriers with extended function. In chromatography for example, there is frequent use of spherical gel particles (e. g. Sephadex), irregular granulates (activated coals, resins, mixed oxides), extruded and compressed substances.sup.1 (molecular sieves, catalysts) or fibers and hollow fibers (Ullmanns Encyclopedia of Industrial Chemistry, Vol. A21, 305-428 (1992) VCH-Publishers Cooperation, as well as in the place cited Vol. B3, 10-1 to 10-44 (1992)). Spherical microparticles are also frequently used in dyestuff production because of their characteristic optical refraction features as a function of their size (e. g. latex or microspherical glasses in or with light reflecting paintings). On the one hand, smaller and smaller particle dimensions (micrometer range, submicrometer range) are sought to be obtained (Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 15, 470-493 (1981), J. Wiley & Sons, New York), or, on the other hand, importance is attributed to a defined size spectrum--up to monodisperse homogeneous mixtures--, in order to obtain, with a given packed volume, larger and larger surfaces for reciprocal effect with the liquid, gas or suspension streaming through.
The size of the exclusively spherical end products in the micrometer or submicrometer range may be strictly determined only by the processing conditions of production or adjusted by subsequent classification. The latter is valid for all irregular particles proceeding from size reduction technologies, but not for their shape. The shape of the microparticles results exclusively from their production technology and is limited to microspheres (balls) by melting technologies for all polymer materials and the aforementioned glasses produced in stirred tank reactors. Only microcrystalline materials are subject to a certain regulation or control, the shapes to be obtained resulting from the projection of the material specific crystal levels and for this reason again being limited.
SUMMARY OF THE INVENTION
It would be of advantage for many application purposes (chromatography, dyestuff and medicament production, etc.) to dispose of microparticles geometrically determinable within wide limits and reproducible, which microparticles at present being producible only in isolated cases with sufficient geometrical variability and structure.
As described by POHL already in 1978 in a monography (POHL, H. P., Dielectrophoresis, Cambridge Press, Cambridge 1978), electric fields can be used for collecting particles and cells in liquid media. For this purpose, he and further authors (e. g. T. B. JONES, J. Electrostatics 18, 55-62 (1986) and others) used in most cases macroscopic electrode arrangements. Under these circumstances, the shaping of bodies was not possible.
The development of high frequency field cages on the basis of microelectrodes produced with semiconductor technology methods represented a decisive step (T. SCHNELLE et al. Biochim. Biophys. Acta 1157, 127-140 (1993)). They served for the trapping and manipulation of cells and very small particles in microchannel and reaction systems and were based on macroscopic field cages as known from high-energy physics (W. PAUL et al., Forschungsberichte des Wirtschaftsministeriums Nordrhein-Westfalen, No. 145 and No. 450 (1958)). It could also be demonstrated that small particles, such as latex spheres having a size of a few micrometers; e.g. 3.4 .mu.m or 9.9 .mu.m, are collected to aggregates in free solution by negatively dielectrophoretic
REFERENCES:
patent: 4092231 (1978-05-01), Chronberg
patent: 4722787 (1988-02-01), Fombarlet et al.
patent: 4929400 (1990-05-01), Rembaum et al.
patent: 5381683 (1995-01-01), Cowling
Central Patents Index Basic Abstracts Journal, Week E10, May 5, 1982, 19618 /10.
Ikuta & Hirowatari, 1993, Real Three Dimensional Micro Fabrication Using Stereo Lithography and Metal Molding, pp. 42-47.
Takagi, et al., Photoforming Applied to Fine Machining, pp. 172-178 (1993).
Boman and Westberg, Helical Microstructures Grown by Laser Assisted Chemical Vapour Deposition, pp. 162-167.
Ullmann's Encyclopedia of Industrial Chemistry, Fifth, Completely Revised
Ullmann's Encyclopedia of Industrial Chemistry, Fifth, Completely Revised
Jones, Dielectrophoretic Force Axisymmetric Fields, 1986, Journ. of Electrostatics.
Fuhr, et al., Levitation, Holding and Rotation of Cells within Traps Made by High-Frequency Fields, 1992, Biochimica et biophysica Acta., 215-223.
Schnelle, et al., Three-Dimensional Electric Field Traps for Manipulation of Cells -- Calculation and Experimental Verification, Biochimica et Biophysica Acta, 1993, 127-140.
Encyclopedia of Chemical Technology, Third Edition, vol. 15., Kirk-Othmer,
Fiedler Stefan
Fuhr Guenter
Glasser Henning
Hagedorn Rolf
Hornung Jan
Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forschung
Mullis Jeffrey
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