Error Recovery in Cyberphysical Digital Microfluidic Biochips

Abstract

Droplet-based "digital" microfluidics technology has now come of age and software-controlled biochips for healthcare applications are starting to emerge. However, today's digital microfluidic biochips suffer from the drawback that there is no feedback to the control software from the underlying hardware platform. Due to the lack of precision inherent in biochemical experiments, errors are likely during droplet manipulation, but error recovery based on the repetition of experiments leads to wastage of expensive reagents and hard-to-prepare samples. By exploiting recent advances in the integration of optical detectors (sensors) in a digital microfluidics biochip, we present a "physicalaware" system reconfiguration technique that uses sensor data at intermediate checkpoints to dynamically reconfigure the biochip. A cyberphysical re-synthesis technique is used to recompute electrode-actuation sequences, thereby deriving new schedules, module placement, and droplet routing pathways, with minimum impact on the time-to-response.

Rapid online fault recovery for cyber-physical digital microfluidic biochips

“…Table 1 lists the algorithms and their relevant properties in comparison to algorithms introduced in this paper. With the exception of Luo et al [14], all of these techniques focus explicitly on hard or soft faults, but not both.…”

“…Their approach had two limitations: (1) all operations stop during recovery, including those that do not depend on droplets involved in the fault; and (2) operations within the error recovery subgraph must be fault-free. Subsequent work has addressed these limitations [14,15].…”

“…Early DMFB compilers dispose of all unneeded droplets, as there was no motivation to store them. Hseih et al [10] and Luo et al [14] optimistically store some of these intermediate droplets, as they can reduce the overhead of the fault recovery process. Our approach can support droplet re-use if desired.…”

“…Recent DMFBs integrate devices such as heaters [13], photo-detectors [14,29], impedance sensors [22], or magnetic separators [6], which provide feedback to a PC that controls the execution of an assay (biochemical reaction) running on the DMFB, forming a feedback-control loop as shown in Fig. 1.…”

An open-source compiler and PCB synthesis tool for digital microfluidic biochips

“…2 shows the basic instruction set of a DMFB, which consists of five operations: droplet transport, splitting, merging, mixing, and storage. Additional operations can be realized by adding external devices to the device such as heaters [45], optical detectors [47,87], integrated sensors [13,57,68], etc. Fig.…”