Dear Kim JaeGu,
we have developed a casting method which resembles LIGA in attainable size and
precision. The basic principle is sustained negative dielectro- phoresis of
suspended particles to assemble them into structured aggregates in
3-dimensional a.c. field cages. These aggregates are than frozen by
polymerization. Differences in permittivity and/or conductivity of liquid and
solid parts of the starting suspension determine the usable a.c.frequency range
(usually kHz to MHz for aqueous suspensions of latex particles, liposomes, ....
and even living cells). Size and shape of the cast microbody depend on the
electrode geometry, gap width and individual amplitude voltages. Microelectrode
arrays assembled into field cage forming 'sand- wiches' allow fabrication of a
wealth of identical microbodies at once. So far, bullet-, cask-, ellipsoid-,
and star-like microbodies have been cast. In the same way surfaces could be
structured. The electrocasting principle could be interesting for sustained
drug release formulation (multilayered microbodies with holes), biotechnology
and MEMS.

Fiedler, S.; Schnelle, Th.; Wagner, B.; Fuhr, G.
Electrocasting - formation and structuring of suspended microbodies using
a.c.generated field cages
Microsystem Technoogies 2 (1995) 1-7
____________________________________________________________________________
Humboldt Universitat Berlin       |
Institut fur Biologie             |   Dr. Stefan Fiedler
Membranphysiologie                |   Tel.: 49 30 2897 2617
Invalidenstr. 43                  |   Fax:  49 30 2897 2635
D-10115 Berlin                    |   E-mail:  Stefan=Fiedler@rz.hu-berlin.de
Federal Republic Germany _________|_________________________________________