Droplet routing and wash droplet scheduling algorithm to remove cross-contamination in digital microfluidic biochip

Abstract

Cross-contamination is incurred during droplet routing in digital microfluidic biochip (DMFB) because of intersection and overlap in the routing paths. Those intersected or overlapped regions are termed as contamination sites. In this paper, we propose a scheme for concurrent routing of multiple droplets with avoidance or minimization in cross-contamination, followed by a wash droplet scheduling operation for residue removal in the contamination sites. The proposed method is based on a hierarchical partitioning method that generates an unbalanced tree structure containing routing nets in the different nodes on the tree. The proposed partitioning technique is guided by the bounding boxes of the routing nets that help in avoiding intersection in routing paths in different partitioned zone/area. During droplet routing, our aim is to optimize resource utilizations, and minimize cross-contamination in a partition. Any cross-contamination site is washed with proper scheduling of wash droplets in the intermediate routing stages, and a shortest path based wash droplet operation is adopted to minimize routing overhead, or total routing completion time. Different observations are made by applying our algorithm on real benchmarks, and experimental results show improvement in many cases.