NR-Router: Non-Regular Electrode Routing with Optimal Pin Selection for Electrowetting-on-Dielectric Chips

With the advances in microfluidics, electrowetting-on-dielectric (EWOD) chips have widely been applied to various laboratory procedures. Glass-based EWOD chips with non-regular electrodes are proposed, which allow more reliable droplet operations and facilitating integration of optical sensors for many biochemical applications. Besides, non-regular electrode designs (e.g., interdigitated electrodes) are utilized in EWOD chips to precisely control droplet volume, and electrodes with a specific shape become necessary for certain applications. However, due to the technical barriers of fabricating multi-layer interconnection on the glass substrate (e.g., unreliable process and high cost), both control electrodes and wires are fabri-cated with a single-layer configuration, which poses significant challenges to pin selection for non-regular electrodes under the limited routing resource. In this paper, we propose a minimum cost flow-based routing algorithm called NR-Router that features efficient and robust routing for single-layer EWOD chips with non-regular electrodes, which overcomes the challenges mentioned above. NR- Router is the first algorithm that can accurately route in single-layer EWOD chips with non-regular electrodes to the best of our knowledge. We construct a minimum cost flow algorithm to generate optimal routing paths followed by a light-weight model to handle flow capacity. NR-Router achieves 100% routability while minimizing wirelength at shorter run time, and generates mask files feasible for manufacturing via adjustments of design parameters. Experimental results demonstrate the robustness and efficiency of our proposed algorithm.