Reliability-Driven Chip-Level Design for High-Frequency Digital Microfluidic Biochips

Electrowetting-on-dielectric (EWOD) chips have emerged as popular actuators for droplet-based digital microfluidic biochips. The chip-level design of EWOD chips allows for the integration electrode addressing and wire routing, thus helping cope with the increasing complexity of biochemical assays. Furthermore, high-frequency EWODs also facilitate finishing time-sensitive bioassays such as incubation and emerging flash chemistry in specific time periods. However, the reliability of the EWOD chip is reduced by the contact angle change reduction problem as a result of the repeated and frequent switching of electrodes. Thus, the chip-level design of EWOD chips should consider reliability, electrode addressing, and the wire routing problem. This paper presents a graph-based chip-level design algorithm. By setting the switching-time constraint, the number of switching times can be limited to minimize the impact of the contact angle change reductions problem. Also, a progressive addressing and routing approach is proposed to overcome the complex wire routing problem. Experimental results show the proposed algorithm effectively minimizes the impact of the contact angle change reduction problem, thus providing a reliable chip-level design with a feasible wire routing solution with the required number of pins.