Hardware Reference
In-Depth Information
To overcome the above drawbacks, we take a transformative “cyberphysical”
approach towards achieving sensor feedback-driven and closed-loop biochip oper-
ations under software control. By exploiting recent advances in the integration of
sensing system in a digital microfluidics biochip [
16
], we present a “physical-aware”
system reconfiguration technique that uses sensor data at intermediate checkpoints
to dynamically reconfigure the biochip [
17
].
2.2
Overview of Cyberphysical Biochips
In this section, we introduce the cyberphysical system on microfluidic biochips and
as well as each component of the system. With the availability of sensing system
for biochips, “physical-aware” control software becomes feasible. By “physical-
aware”, we refer to the fact that the software can receive information about the
outcome (error-free/erroneous) of fluid-handling operations based on feedback
from the sensing system. Depending on sensor feedback, the control software will
appropriately reconfigure the microfluidic biochip. In this way, the various steps in
the bioassay are executed based upon real-time sensing of intermediate results.
Figure
2.2
depicts each component of a cyberphysical system on the microfluidic
platform. The control software sends a control signal to the microfluidic biochip,
and the on-chip sensing system monitors the outcomes of fluidic operations.
The outcomes are compared with the “expected values”, i.e., the pre-determined
thresholds. If the results of the comparison indicate that an error has occurred, the
control software receives a “repeat request”, and the corresponding operation in
which the error occurred can be executed again. In this way, the error will be
corrected.
2.2.1
Sensing Systems
Two sensing schemes can potentially be used in the cyberphysical system on digital
microfluidic biochips.
Comparator
Thresholds at
checkpoints
Output
droplets
Input to the
biochip
Measured
error
Ref
Microfluidic
biochip
Control
software
Feedback
Integrated
sensor
Measured output
