Hardware Reference
In-Depth Information
Tabl e 3. 11
Compaction ratios of actuation matrices of an assay in flash
chemistry
No. elements
No. non-zero
Errors
Bioassay
in the dictionary
elements in the
inserted
time (s)
entry
dictionary entry
R
I
R
II
M
2
in
S
1
0.32
3,200
93
11.47
11.19
M
4
in
S
1
0.25
2,500
86
9.69
9.19
M
1
in
S
2
0.19
1,900
94
6.73
6.60
M
2
in
S
0.19
1,900
87
7.28
6.93
2
3.8.5
Flash Chemistry
As introduced in [
33
], a microfluidic biochip is one of the promising hardware
platforms for flash chemistry. In this subsection, the simulation results for two
representative assays of flash chemistry are presented. These two assays are
“synthesis of unsymmetrical diarylethenes” (
S
1
) and the “bromine-lithium exchange
reaction of o-dibromobenzene” (
S
2
can
be found in Fig.
3.11
[
33
]. We assume that the two assays are concurrently executed
on a 10
10 electrode array.
It is important to note that the “microtube reactors” shown in Fig.
3.11
can
be viewed as time controllers of reactions in flash chemistry. Since the reaction
time can be easily controlled on a digital microfluidic biochip (for example, we
can merge two reagent droplets together at a pre-determined time moment to
start the reaction, and separate the droplets at a given time moment to end the
reaction), in the synthesis procedure, we consider “reactors” as the same module for
mixing operation, and not assign specific “reactors” on the biochip. Therefore, the
assay “synthesis of unsymmetrical diarylethenes” includes four mixing operations
and five dispensing operations for five different kinds of reagents/samples; the
assay “bromine-lithium exchange reaction of o-dibromobenzene” includes two
mixing operations and three dispensing operations for three different kinds of
reagents/samples.
The reaction times in flash chemistry usually are very short. Here we assume that
the working frequency of the biochip is 100 Hz, and each mixing operation on a
2
4 array takes 40 ms [
33
]. Since dispensing each reagent/sample droplet takes 4
clock cycles [
24
], the completion time for each dispensing operation is set as 40 ms.
In the error-free case, the completion time of these three bioassay is 190 ms.
As the total number of operations in the “combined bioassay” is 14, the number
of dictionary entries we generated is
S
2
)[
33
]. The sequence graphs for
S
1
and
N
e
D
14
C
.14
13/=2
D
105. The average
response time for the proposed method is nearly zero. We have also derived the
compaction ratios for all the dictionary entries. Part of the simulation results can
be found in Table
3.11
. For this small assay, Method I is more effective than
Method II.
