Biomedical Engineering Reference
In-Depth Information
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Reservoirs
Figure 4.39
Fabricated biochip for PCR.
4.6 Experimental and Simulation Results
In this section, we apply the proposed functional test methods to a fabricated
chip. The chip under test is a PCB microfluidic platform for the polymerase
chain reaction (PCR), as shown in Figure 4.39. The platform consists of two
columns and two rows of electrodes, three reservoirs, and routing electrodes
that connect the reservoirs to the array.
We applied the proposed functional test methods to this chip. The dis-
pensing test and routing test are trivial due to the simple structure of the
chip. Therefore, we only focused on the mixing and splitting test. Following
the steps in Subsection 4.5.3, we first targeted the bottom row and dispensed
five test droplets to the odd electrodes, as shown in Figure 4.40a. Then, the
splitting test of the even electrodes was carried out. Droplets were split and
merged on the even electrodes. In Figure 4.40b, we see a series of droplets
of the same volume resting on the even electrodes, which means that all
the odd electrodes passed the splitting test, and merging at the even elec-
trodes worked well. However, when we carried out the splitting test on the
even electrodes, a large variation in droplet volume was observed on the 3rd
and 5th electrodes
(see Figure 4.40c)
. This variation implied a malfunction,
leading to unbalanced splitting on the 4th electrode. The malfunction was
detected when the droplets were routed to the capacitive sensing circuit. We
then labeled the 4th electrode on the bottom row as an unqualified split-
ting site so that synthesis tools will not map a splitter to it. Thus, the system
robustness of the synthesized design was enhanced.
We next evaluate the improvement in system robustness using a biochip
for the protein dilution assay described in Chapter 2. Again, a 10 × 10 micro-
fluidic array is used to execute the assay.
