Hardware Reference
In-Depth Information
(1.a) E
11
and E
12
are non-diagonally adjacent electrodes: In this case, the move-
ment of a droplet along some directions cannot be achieved due to the electric
shorting of adjacent electrodes [
10
].
(1.b) E
11
and E
12
are diagonally adjacent electrodes: An example can be found in
Fig.
6.1
c. Two non-diagonally adjacent electrodes of the droplet are controlled by
Pin A. If “High” signal is applied to Pin A, the two electrodes that are connected
to Pin A will pull the droplet from two directions at the same time. The droplet
may undergo unwanted and unpredictable movement.
(1.c) E
11
and E
12
are non-adjacent electrodes: An example is shown in Fig.
6.1
d.
Two non-adjacent electrodes of the droplet are controlled by Pin A. The droplet
may be split if Pin A activates the two electrodes at the same time.
According to the above discussion for Cases (1.a)
(1.c), we conclude that in
order to avoid unwanted movement or splitting of droplets and also guarantee the
flexibility of droplet movements, electrodes in the same CEG cannot share control
pins.
Next we assume that CEG
1
and CEG
2
share one pin (without loss of generality,
we assume that the shared pin is Pin A). Then we have the following scenarios,
exhaustively enumerated by Cases (2.a)
(2.c):
(2.a) Pin A is connected to both E
1C
and E
2C
: An example can be found in
Fig.
6.2
a. The two droplets can be moved concurrently to any non-diagonally
adjacent electrode without pin-actuation conflicts. Thus, there are 16 possible
concurrent movements of the pair of droplets, and no unwanted movement or
splitting will occur for these 16 concurrent movements.
(2.b) Pin A is neither connected to E
1C
nor E
2C
: An example can be found
in Fig.
6.2
b. Suppose Droplet 1 and Droplet 2 are scheduled to move in the
directions indicated by the arrows. For the movement of Droplet 1, the control
voltages applied to Pins A, B, C, D, and E should be set as “High”, “Low”,
“Low”, “Low”, and “Low”, respectively. Similarly, for the movement of Droplet
2, the control voltages on Pins A, F, G, H, and I should be set as “Low”, “Low”,
“Low”, “High”, and “Low”, respectively. Thus the status of Pin A corresponding
to the movements of Droplet 1 and Droplet 2 are different. In order to avoid
a conflict, Droplet 1 and Droplet 2 must be moved in different clock cycles.
Assume that Droplet 1 is moved first; a “High” voltage will be applied to Pin
A. To keep Droplet 2 stay at its current position, a “High” voltage will also be
applied to the electrode under Droplet 2 (i.e., a “High” voltage will be applied to
Pin F). Note that when a high voltage is applied to the electrode under the droplet,
the droplet will remain at its current position without movement or splitting,
even if high voltage is applied to one of its adjacent electrodes; this scenario
has been experimentally demonstrated [
11
]. After Droplet 1 has arrived at its
destination electrode, the movement operation for Droplet 2 will be performed.
Thus, the number of all possible concurrent movements for the droplet pair is
1
C
3
3
D
10, and no unwanted movement or splitting will occur for these 10
concurrent movements.
