Unified Contamination-Aware Routing Method Considering Realistic Washing Capacity Constraint in Digital Microfluidic Biochips

Abstract

To fully utilize the dynamic reconfigurability of digital microfluidic biochips, most of electrodes would be shared by different droplets. Thus, contaminations caused by liquid residues among droplets are inevitable which lead to lethal errors in bioassays. To remove the contaminations, washing operations are introduced as an essential step to ensure the correctness of bioassay. However, existing works have oversimplified assumptions on the washing droplet's behavior and constraints which cannot clean all contaminations with erroneous outcomes. Moreover, straightforward integration of washing operations with droplet routing may increase the execution time of a bioassay which is not feasible for timing-critical bioassay. To effectively remove contaminations and minimize the execution time of a bioassay, this paper proposes a unified contamination-aware routing method, which addresses the above issues simultaneously. Firstly, we present a top-down scheme to generate candidates of routing paths, then construct a shortestpath model to select desirable routing solution for all subproblems. With a decision diagram of droplets, we further propose an integer linear programming (ILP) formulation to compact the execution time. Finally, contamination removal by washing droplets with realistic washing capacity is considered for all subproblems. Tested on real-life benchmarks, our proposed method can significantly reduce 72% contamination spots and save 11% execution time. INDEX TERMS Digital microfluidic biochip, dynamic reconfigurability, washing operations, contamination aware routing, integer linear programming.

An MMSPEED based droplet Routing protocol for Digital Microfluidic Biochip

“…The two swarm intelligence based protocol are Pan router [9] based on ant colony optimization and Juarez router [12] based on genetic algorithm. We have also performed comparison with six traditional popular methods like Grissom et al [8], Swain et al [11], Huang et al [7], Cho et al [6], Roy et al [10] and Su et al [5]. Grissom et al [8] is defined for virtual topology while Swain et al is tailor-made for free topology.…”

“…Grissom et al [14] controls the rate of flow droplets to avoid congestion problem. Both the works [7], [14] suffers from bottleneck of placement of modules, droplet injection rate or storage issues, that leads to the complacency in converting routing problem in flow models. Roy et al [10] and Swain et al [11] presents graph based solutions.…”

“…It has optimal value for in-vitro 4 benchmark. Huang router [7] able to run all the benchmarks except protein split 4,5,6 and 7. It has best LAT values PCR and protein split 3.…”

“…The bottom plate consists of multiple equally spaced uniformed sized control electrodes. The space between the plates can filled up with normal air or silicon oil [7], [8], [12]. Fluid droplets are sandwiched between these plates.…”

“…Digital Microfluidic Biochip (DMFB) or Biochip is one of the recent trending research area . DMFB offers an alternate platform to perform biochemical reactions than traditional biochemical laboratory [5], [7], [8]. The main advantages of Biochip are dynamic configuration, portability, precision analysis and on-spot analysis .…”