Information Technology Reference
In-Depth Information
Early research on CAD for digital microfluidics-based biochips has been focused
on device-level physical modeling of single components. In modern days a top down
system design and test methodology that attempts to apply classical synthesis
techniques has been used for the design of digital microfluidics-based biochips. This
methodology speeds up the design cycle, reduces human
effort, and increases
dependability [11].
A behavioral model for a biomedical assay is first manually obtained from the
protocol for that assay. Next, architectural-level synthesis is applied to generate a
macroscopic structure of the biochip. The macroscopic model provides an assignment
of assay functions to biochip resources, as well as a mapping of assay functions to
time-steps, based in part on the dependencies between them. Based on the scheduling
results, placement algorithms are applied to generate a suitable layout for allocating
droplets and modules [12] followed by necessary compaction. Finally droplet-routing
algorithms are used to formulate droplet behaviors in a reconfigurable manner for
concurrent time multiplexed routing within a 2D planar array of DMFB. The second
phase of chip-level design determines the control-signal plan for the underlying
electrodes to execute the synthesized result. This phase known as geometry-level
synthesis creates a physical representation at the geometrical level. A block level
design flow diagram for DMFB design is shown in figure 2. The output is the final
layout of the biochip consisting of the configuration of the microfluidic array,
locations of reservoirs and dispensing ports, and other geometric details. However it
has been found that for all types of microfluidic operation at any given time only one
to three electrodes are actually required. Hence it may be possible to dynamically
reconfigure any group of cells for performing DMFB operations -in spite of reserving
fixed locations for specified operations. In this paper we have proposed a scheduling
algorithm to determine a sequence for bioassay operation that can be executed in a
time multiplexed manner dynamically at next available locations within the 2D planar
array. We further proposed a placement technique for tentative assignment of
locations to perform the operations dynamically for a group of predefined nets
obtained from the bioassay behavioral model through architecture level synthesis. It
has been shown that the method resolves the resource constraint problem for
scheduling a bioassay (enhancing execution of microfluidic operations
simultaneously) and reduces the overall execution time as well as optimizes the total
area to be assigned for the completion of the specified Bioassay protocol.
The organization of the paper is as follows. Section 2 discusses the contemporary
contribution on scheduling and placement of biochips. Section 3 describes the details
of the reconfigurable transportation based operation and necessary fluidic constraints
in DMFBs. Section 4 states the basic scheduling methodology for a given bioassay
application. Section 5 defines the proposed method for dynamic scheduling followed
by nonreconfigurable resource assignment and final placement within the 2D planar
array. Section 6 displays the experimental results for execution of the proposed
scheduling and placement techniques employed on PCRs involving different sets of
samples and reagents. Section VII presents the conclusive remarks and future scope
for further extension of the presented work
