Biomedical Engineering Reference
In-Depth Information
Even electrodes
Odd electrodes
Splitting
Mixing
Figure 4.33
The parallel mixing and splitting test for a row of electrodes.
each mixing or splitting test step is represented by a pair of directed edges
(see Figure 4.33) .
The electrodes in Figure 4.33 are labeled as being either “even” or “odd.”
We carry out the horizontal splitting test for all the even electrodes concur-
rently. The split droplets get merged at the odd electrodes; therefore, the
merging test is done at the same time. Similarly, by carrying out the splitting
test for all the odd electrodes concurrently, we can easily complete the hori-
zontal merging test for all the even electrodes. Thus, we can carry out all the
horizontal tests (merging and splitting) in one row using only two manipu-
lation steps. Similarly, all the vertical tests in one column can be completed
in two manipulation steps.
Following the preceding observations, we propose a parallel procedure to
carry out mixing and splitting tests efficiently. The steps of the procedure
are as follows:
1. Route large droplets to all the even electrodes in a row.
2. Carry out the splitting test for all the even electrodes concurrently
(large droplets are now on odd electrodes).
3. Carry out the splitting test for all the odd electrodes concurrently
(large droplets are now on even electrodes).
4. Route the droplets consecutively to a capacitive sensing circuit for
test readouts.
5. Repeat the test procedure for the next row.
6. Repeat steps 1-5 for columns.
Note that in the preceding method, only one capacitive sensing circuit is
used; therefore, the hardware cost is significantly reduced. However, addi-
tional droplet-routing steps are needed. In order to minimize the number of
droplet manipulations, test results are read out not directly after each split-
ting or merging test but after the both of them are carried out, as shown in
 
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