Biomedical Engineering Reference
In-Depth Information
8
Power-ecient method
Power-oblivious method
[58]
6
4
2
0
1
2
3
4
Subproblem #
Figure 3.30
Comparison of average # of control pins activated per manipulation step for the power-efficient
method, the power-oblivious method, and the method from [63].
results in increased power consumption compared to the power-efficient
method. However, the power consumption is still much smaller than in [63].
3.3 Broadcast-Addressing Method
In this section, we introduce an alternative pin-constrained design scheme
referred to as the broadcast-addressing method [64]. The proposed method
provides high throughput for bioassays, and it reduces the number of
control pins by identifying and connecting control pins with “compatible”
actuation sequences.
3.3.1 “Don't-Cares” in electrode-Actuation Sequences
To execute a specific bioassay, droplet routes and the schedule of operations are
prog ra m me d i into a m ic ro cont rol ler to d r ive t he ele c t ro de s. Rout i ng a nd s c he du l-
ing information is stored in the form of (ternary) electrode-activation sequences,
with each bit representing the status of the electrode at a specific time step. The
status can be either “1” (activate), “0” (deactivate), or “x” (don't-care).
A don't-care status on an electrode means that the electrode can be either
active or inactive, as shown in Figure 3.31. At time spot t , a droplet is to be held
at electrode E 3 . This electrode needs to be at high voltage (“1”), and the two
adjacent electrodes E 2 and E 4 need to be deactivated (“0”). E 1 is not involved
in this holding step. Since the voltage on E 1 has no impact on the droplet
operations for this step, E 1 can be assigned “1” or “0,” that is, “don't-care”
or “x.” This concept is similar to the don't-cares that arise in logic synthesis
during integrated circuit design.
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