Background, Motivation and Objective The development of perfluorocarbon nanodroplets (PFC NDs) as in situ microbubble precursors for ultrasound imaging and therapy is an active area of research. For applications in cancer, the NDs size, ranging from ~200 to 400 nm in diameter, means that, unlike larger, less stable microbubbles that are purely intravascular, longcirculating PFC NDs can leak from blood vessels into the interstitial space in solid tumours. After accumulation into tumours, these PFC NDs can be activated by ultrasound or light, to undergo phase change in situ to form echogenic bubbles. Despite early promising preclinical results, it is clear that the successful translation of these PFC NDs into clinical use will require substantial improvements in the controlled synthesis of PFC NDs of specific sizes for predictable tumour accumulation and efficient conversion into bubbles. In this study, we evaluate the feasibility of adapting current microfluidic methods to engineer highly size-controlled PFC NDs for the practical design of future, clinically-translatable PFC NDs for cancer therapy.