Synchronization of washing operations with droplet routing for cross-contamination avoidance in digital microfluidic biochips

Digital microfluidic biochips are being utilized in many areas of biochemistry and biomedical sciences. Since cross-contamination between droplets of different biomolecules can lead to erroneous outcomes for bioassays, it is essential to avoid cross-contamination during droplet routing. We propose a wash-operation synchronization method to manipulate wash droplets to clean the residue that is left behind by sample and reagent droplets. We also synchronize wash-droplet routing with sample/reagent droplet-routing steps by controlling the arrival order of droplets at cross-contamination sites. The proposed method minimizes droplet-routing time without cross-contamination, and it is especially effective for tight chip-area constraints. A real-life application is used for evaluation.