Hardware Reference
In-Depth Information
b
Dispense Dispense
Dispense Dispense
3
4
1
2
Mix 1
Mix 2
a
7
8
Dispense Dispense
Dispense Dispense
Dispense Dispense
Mix 4
10
3
4
1
2
5
6
Mix 2
Mix 1
7
8
Mix 3
9
Dispense Dispense
Mix 4
10
Dispense
Dispense
5
6
13
12
Mix 3
9
14
Mix 5
Mix 5
11
11
Fig. 2.1
(
a
) Initial sequencing graph; (
b
) operations 12, 13, and 14 are added for error-recovery
1. The first drawback is the over-simplification of fault detection and the associated
assumptions. It is impractical to use a uniform “expected value” for the cali-
bration of each detection operation. Note that the concentration of intermediate
product droplets vary in a dynamic manner at various stages during bioassay
execution. Hence the calibration needs to be repeated and carried out dynamically
as well.
2. In [
11
], all recovery operations are carried out in a stand-alone manner. All
other ongoing bioassay-related fluidic operations are interrupted when an error is
detected. The potential long waiting times introduced by recovery operations will
lead to sample degradation and erroneous assay outcomes [
14
]. Some operations,
such as colorimetric enzyme-kinetic reactions, require precise durations as spec-
ified by the reaction protocol, and they cannot be elongated without introducing
unpredictability in the experiment outcome [
15
].
3. The error-recovery approach in [
11
] cannot handle situations when multiple
errors occur during a bioassay. For example, [
11
] assumes that all error-recovery
operations will be executed successfully and it does not consider the likelihood
that errors can also occur during recovery.
4. The error-recovery strategy in [
11
] does not consider reliability issues. Errors
such as the generation of droplets with abnormal volumes are usually caused by
the accumulation of charge on the surface of certain electrodes [
7
,
8
]. If the use
of such electrodes is continued, it is likely that they will introduce more errors
[
7
,
8
]. Thus, in order to ensure the reliability of biochips, we must minimize the
utilization of these electrodes.
