Microfluidic biochips are revolutionizing many areas of biochemistry and biomedical sciences. Several synthesis tools have recently been proposed for the automated design of biochips from the specifications of laboratory protocols. However, only a few of these tools address the problem of droplet routing in microfluidic arrays. These methods typically rely on post-synthesis droplet routing to implement biochemical protocols. Such an approach is not only time-consuming, but it also imposes an undue burden on the chip user. Moreover, post-synthesis droplet routing does not guarantee that feasible droplet pathways can be found for area-constrained biochip layouts; non-routable fabricated biochips must be discarded. We present a droplet-routing-aware automated synthesis tool for microfluidic biochips. Droplet routability, defined as the ease with which droplet pathways can be determined, is estimated and integrated in the synthesis flow. The proposed approach allows architectural-level de...