Biomedical Engineering Reference
In-Depth Information
Source
Sink
Untestable site
Defect sites
Figure 4.14
An example of an untestable site.
Sink
Figure 4.15
Illustration of a diagonal parallel scan-like test.
to this test iteration as a diagonal test, as shown in Figure 4.15. In the addi-
tional test iteration, multiple test droplets are manipulated to traverse the
array from one diagonal direction (top-left to bottom-right, or top-right to
bottom-left) or both, referred to here as a
single-diagonal test
and
cross-diagonal
test
,
respectively. Untestable sites that cannot be reached from vertical and
horizontal directions can be reached diagonally. Even though this approach
cannot guarantee the testability of all the untestable sites, it significantly
reduces the probability that an electrode site is untestable.
Another advantage of the diagonal test procedure is that it can also help
in avoiding incorrectly classified defect sites. Only the sites that lie on fail-
ing columns, failing rows, and failing diagonals are identified as defects.
Although this method does not completely eliminate the likelihood of incor-
rectly classified defects, it provides an acceptable diagnostic resolution by
eliminating most incorrectly classified defects. These advantages are high-
lighted quantitatively in Subsection 4.3.2.
