A microfluidic device for quantification of atmospheric ice-nucleating particles (FluidIce)

A small fraction of atmospheric aerosol particles that nucleate ice in clouds have a disproportionate effect on climate. Quantification of these ice-nucleating particles is key to reducing climate uncertainties associated with clouds around the globe, from deep convection in the tropics to boundary layer clouds in the oceanic mid- to high-latitudes. However, the atmospheric concentration, sources, sinks, transport and activity of ice-nucleating particles are all poorly defined. A major limitation is the lack of instrumentation capable of measuring ice-nucleating particles. We have previously developed a prototype microfluidic platform for quantifying atmospheric ice-nucleating particles in Murray's European Research Council fellowship, but its throughput and automation are limited by both instrumental and data processing challenges. Here we propose to take LOC-NIPI far beyond what was envisaged in Murray's ERC grant and to vastly improve it utility for the quantification of atmospheric ice-nucleating particles.

In FluidIce we will replace the data-hungry (and limiting) high speed camera with a much simpler LED-Photodiode detector coupled with our new frozen-unfrozen droplet sorting device. This relatively modest investment will allow us to greatly speed up sample throughput and therefore add a great deal of value to other projects, such as M-Phase (a NERC grant focused on the cloud-phase feedback as part of the CloudSense programme) and WesCon (a Met Office funded aircraft project looking at high-impact convection in the UK).

The legacy of FluidIce will make the routine quantification of ice-nucleating particles concentrations down to ~−35 °C possible in future field and laboratory projects. FluidIce also moves the LOC-NIPI towards our longer term goal of a fully automated instrument capable of continuous monitoring of ice-nucleating particle spectra, from sampling through to freezing analysis.