each other, creating a microarray. Microarray has also been fabricated on filter
membranes by sandwiching it between two layers of PDMS containing two differ-
entμFNs [ 95 ]. The major advantage of these systems is the elimination of the need
to remove the firstμFN and the subsequent introduction of the second onto the
pattern.
4.2 Bead-Based Multiplexing
The simplest way of multiplexing bead-based immunoassays is to separate beads
with different conjugated antibody into sets, and isolate each set of beads in
Fig. 9.5 Patterning of
surface using microfluidic
networks. (a)AμFN
patterned different protein
analytes along lines on a
substrate. (b) Unpatterned
area was blocked with BSA.
(c) Flourescently-labeled
antibodies flowed through
the channels of a second
μFN and locally bind to the
patterned analytes. (d)
Immunocomplex formation
resulted in fluorescent spots.
(e) Microsopy image of the
microspot patterns. Taken
from [ 91 ]. Copyright
©2001 American Chemical
Society
238 A. Ng