10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Microfluidic Ice Nucleating Particle Counter for Continuous Measurements
Ali Mohammadi Nafchi, Gavin McMeeking, ANDREW METCALF, Clemson University
Abstract Number: 1289 Working Group: Unraveling the Many Facets of Ice Nucleating Particles and Their Interactions with Clouds
Abstract Droplet freezing experiments have been of interest for many years because of the difficulty in describing ice formation in the atmosphere with a single theoretical model. The majority of these experiments are conducted in a chamber or flow tube on a population of particles to determine parameters necessary for modeling ice nucleation in the atmosphere. Recent advancements can examine freeze-thaw cycles in single droplets on a microscope cold stage using oil immersion techniques. The techniques currently employed by the community are typically only capable of batch measurements, and the sum of many measurements represents the behavior of a population of ice nucleating particles.
In this talk, we present a new technique to provide continuous measurements of droplet freezing and thawing events, with the ultimate goal of continuously counting ice nucleating particles (INP). Droplet microfluidics are combined with on-chip temperature measurements and a multi-zone cold stage to continuously generate, freeze, and thaw liquid droplets. Temperature control to at least -40 degrees C will allow homogeneous freezing of pure water droplets with rapid repeatability. The microfluidic device includes an embedded platinum resistance temperature detector array which precisely measures temperature at 19 points along the fluid flow channel. The microfluidic device sits on a temperature control block which has 7 discrete temperature zones capable of causing a temperature gradient along the fluid flow. Multiple temperature zones allow hot-cold-hot hysteresis cycles to be observed in single droplets. Initial experiments with this new platform include high-speed observations of droplet freezing at a range of temperatures and INP concentrations.