A Novel Droplet Routing Algorithm with Behavioral Performances in Hexagonal Electrode based DMFB

Recent advances in digital microfluidic biochips or DMFBs have enabled its application in biochemistry, clinical diagnosis, high-throughput DNA sequencing, immunoassays, protein crystallisation, etc. DMFBs ushered in a new era in this domain by establishing a μ-lab-on-chip as a replacement for typical laboratory systems. Handling nanolitre or microlitre volumes of several discrete biochemical fluids is a challenging problem in DMFB synthesis. To address this issue, in this paper, we have proposed to replace the commonly used square electrode cell used in traditional DMFBs with a regular hexagonal one and analysed the critical factors required to perform modular operations safely in the proposed chip array. On-chip droplet routability is also crucial to find out the droplet pathways, which satisfy the constraints imposed by fluidic properties. In this work, we have demonstrated a systematic droplet routing on a hexagonal electrode based DMFB or an HDMFB layout. The proposed algorithm optimises the droplet flow paths by considering all obstacles during the assay runtime; it finds several droplet routes and finally searches for the shortest path that utilises the minimum number of electrodes to reach the target. Some bioassays have been expanded as test cases for evaluating the correctness of the proposed droplet routing algorithm compared to those using traditional square electrode cell, and the obtained results are satisfactory.