Biomedical Engineering Reference
In-Depth Information
Routed to the 1st
functional unit
Te st
droplet
Splitting test
Merging test
Routed to next
functional unit
Splitting test
Euler path
Merging test
Routed back to
detection site
(a)
(b)
Figure 5.6
(a) The mixing and splitting test of functional units along the Euler path of a chip and (b) testing
functional units in groups of two.
two target applications: a multiplexed immunoassay and the polymerase
chain reaction (PCR) procedure.
Each assay is first mapped to a 15 × 15 electrode array controlled using the
direct-addressing scheme. Unused electrodes are removed from the array,
resulting in irregular chip layouts. Next, the presented Euler-path-based
functional test method is applied to obtain a test plan for the chip. Finally,
the test-aware design method is used to generate a pin-constrained design
with a high level of testability.
5.3.1 Multiplexed Assay
We first map the multiplexed biochemical assay described in Chapter 3,
Section 3.4. This assay is used for in vitro measurement and other antigens
in human physiological fluids, which is of great importance for clini-
cal diagnosis. For instance, a change in regular metabolic parameters in a
patient's blood can signal organ damage or dysfunction prior to observable
microscopic cellular damages or other symptoms. A portable, inexpensive
biochip can be used for carrying out multiplexed bioassays for rapid and
point-of-care diagnosis of such disorders. The flowchart for the multiplexed
assays has been shown in Figure 3.34 (Chapter 3) in the form of a sequenc-
ing graph. A depiction of the droplet pathways for multiplexed glucose and
lactase assays has been given in Chapter 3, Figure 3.11.
Next, we apply the Euler-path-based functional test method to the preced-
ing chip layout. To investigate the influence of the number of electrodes in
