Cross-contamination avoidance for droplet routing in digital microfluidic biochips

Recent advances in droplet-based digital microfluidics have enabled biochip devices for DNA sequencing, immunoassays, clinical chemistry, and protein crystallization. Since cross-contamination between droplets of different biomolecules can lead to erroneous outcomes for bioassays, the avoidance of cross-contamination during droplet routing is a key design challenge for biochips. We propose a droplet-routing method that avoids cross-contamination in the optimization of droplet flow paths. The proposed approach targets disjoint droplet routes and minimizes the number of cells used for droplet routing. We also minimize the number of wash operations that must be used between successive routing steps that share unit cells in the microfluidic array. Two real-life biochemical applications are used to evaluate the proposed droplet-routing methods.