A Microfluidic Ice Nucleating Particle Counter for Continuous Measurements from Small Aerial Platforms

Quantifying atmospheric aerosol, clouds and precipitation processes are critical needs for understanding and interpreting Earth’s changing energy budget, is a DOE objective, and is of broader benefit to the public. Specifically, the formation of ice in the atmosphere depends on the nature and abundance of ice nucleating particles, and has major implications for precipitation and cloud interactions with incoming solar radiation. Improved observational capabilities are required to advance understanding of ice nucleating particles, and there is a substantial gap between current needs and existing instruments, particularly those suitable for newly developed unmanned platforms. This project develops a new commercial instrument for measuring ice nucleating particles based on microfluidic techniques, which involve manipulating fluids on sub-millimeter scales. The small size and power requirements possible thanks to the use of microfluidic methods allow for the development of an instrument small enough for use on unmanned platforms. Phase I work established that a simple microfluidic device generated a stable output of droplets that were cooled and frozen at controlled temperatures, and that the device could be connected to a continuous aerosol collection system. Phase II will involve a) further developments and testing of microfluidic devices; b) developing miniature collection, cooling, and detection systems; c) developing electronics and software to control these systems; and d) building and evaluating a prototype instrument. The overall goal is to produce an instrument capable measuring INP from 0 to -38 °C from Unmanned Aerial Systems (UAS). Proven measurement techniques currently used to measure ice nucleating particles from aircraft, including filter sampling followed by offline analysis and continuous flow diffusion chamber measurements will be used to assess the performance of the prototype instrument. Future commercial applications include use by atmospheric researchers seeking to make measurements with UAS or manned research aircraft, as well as those interested in a robust, easy-to-use ground-based instrument for laboratory and field studies. Other applications include the weather modification community, which is interested in ice nucleating particles and their ability to initiate precipitation in clouds.