Biomedical Engineering Reference
In-Depth Information
Direct-addressable chip
Pin-constrained chip
140
120
100
80
60
40
20
0
1
2
3
4
1: n -phase-bus chip
2: array-partitioning-based chip
3: cross-referencing-based chip
4: broadcast-addressing-based chip
Figure 4.44
Number of droplet-manipulation steps for the functional test of direct-addressable and
pin-constrained chips.
Moreover, the reduction in test concurrency can be avoided by increasing
the test frequency.
Another important critical quality to measure the extended functional
test method for pin-constrained designs is testability. As mentioned in
Subsection 4.5.4, due to the connection constraints, not all the electrodes on
a pin-constrained array can be tested. Therefore, we define testability as the
ratio of the number of testable electrodes to the total number of electrodes
in the array. High testability indicates that the test method can probe the
functionality of the chip thoroughly and identify a large number of quali-
fied regions for a target application, which in turn contributes to increased
flexibility for design and fault tolerance. Here, we calculate testability for the
four pin-constrained designs. Results are shown in Figure 4.45.
Figure 4.45 shows that the proposed functional test method achieves high
testability (> 80%) on the n -phase chip, the cross-referencing-based array,
and the broadcast-addressing-based array.
The testability for the array-partitioning-based chip appears to be low.
This is because on an array-partitioning-based chip, the mixing and splitting
operations are only allowed on the boundary cells. If we take this restriction
into account, the testability is as high as 100%.
4.7 Chapter Summary and Conclusions
We have proposed an efficient test and diagnosis method for digital micro-
fluidic biochips. The proposed method enables parallel testing using
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