Microfluidic platform for coupled studies of freezing behavior and final effloresced particle morphology in Snomax^® containing aqueous droplets

Aerosol physicochemical mixing state, defined as the chemical, phase, and internal structure of a population of aerosols, is complex and under-characterized regarding its role in the atmosphere. The compositional and microphysical properties of the aerosol particle strongly impact its atmospheric processes, including water uptake and ice nucleation (IN) activities. However, the relationship between IN activity and particle microphysics remains underdeveloped, as the aerosol particle IN activity, composition, morphology, and size are highly intercorrelated. In this article, we demonstrate the efficacy of a microfluidic static well trap device for testing both IN activity and effloresced residual particle morphology in the same droplet. We link cationic composition with both IN activity and residual particle morphology in droplets containing sodium chloride, calcium chloride, and the biological ice nucleating particle (INP) Snomax. Finally, we show a decoupling between IN activity and residual particle morphology within the same droplet for the chemical systems studied here.