Rapid and inexpensive testing of lipid nanoparticle (LNP) formulations has largely been accomplished using hand-mixing of the components with a typical laboratory pipette. While this method does generate encapsulated cargo, the user-to-user variability and resulting larger particles with higher polydispersity make it less effective and scalable than microfluidics-based methods. We tested single-use centrifugation-based microfluidics devices for screening several LNP formulations. Using these devices, we evaluated standard mRNA formulations as well as the incorporation of 9(10)-nitrooleic acid (NOA) and DOTAP into pDNA cargo formulations. Application of these methods to screening of formulations promises to enhance the speed of innovation in the field and lower the barrier to entry for researchers interested in applying LNPs to their research problem.