Hardware Reference
In-Depth Information
Fig. 1.14
Cross-section view
of a cross-referencing
biochip [
45
]
a
Glass
z
Droplet
x
Glass
b
Glass
z
Droplet
y
Glass
Hydrophobic
coating
Electrodes
Dielectric layer
Fig. 1.15
An example of
unwanted droplet splitting on
the cross-referencing
biochip [
53
]
From the above discussion, it is apparent that the cross-referencing design can
greatly reduce the number of pins for a large-scale biochip. For a digital microfluidic
biochip with m
n cells, a direct addressing biochip requires m
n pins, while a
cross-referencing biochip only requires .m
C
n/ pins.
By connecting multiple columns/rows to the same control pin, the number of
control pins on a cross-referencing can be further reduced [
53
]. However, this design
may lead to unwanted movement or splitting of the droplets. Figure
1.15
[
53
]shows
an example of this situation. On the biochip, row 3 and row 5 are controlled by a
single pin. Assume that the droplet on cell (4, 2) (i.e., the cell in the fourth row and
second column) is to be moved to cell (5, 2). Since rows 3 and 5 are controlled by
the same pin, cell (2, 3) is also activated, and the droplet will be split. In fact, in this
layout, no droplet can reach any of the electrodes on row 5.
