On-chip analysis of atmospheric ice-nucleating particles in continuous flow

Abstract

<p>Ice-nucleating particles (INPs) are of atmospheric importance because they catalyse freezing of supercooled cloud droplets, strongly affecting the lifetime and radiative properties of clouds. There is a need to improve...</p>

On-chip density-based sorting of supercooled droplets and frozen droplets in continuous flow

“…A detailed description of the experimental setup ( Fig. 2b) is provided in section 8 of the ESI, † and largely employed the apparatus and setup of the LOC-NIPI described by Tarn et al 34 Polyethylene tubing (0.38 mm i.d. × 1.09 mm o.d.)…”

“…The microfluidic chip design was adapted from the continuous droplet freezing design of Tarn et al, 34 with the downstream addition of a wide separation chamber and corresponding inlet and outlet channels (Fig. 1c).…”

“…The microfluidic device was fabricated in PDMS, as described by Tarn et al, 34 using standard soft lithography techniques. [68][69][70] A detailed description of the process is provided in section 8 of the ESI.…”

“…for the generation and freezing of water-in-oil droplets for ice-nucleating particle analysis, the Lab-on-a-Chip Nucleation by Immersed Particle Instrument (LOC-NIPI). 34 In the new device described here, the generated ice crystals and supercooled water droplets enter a downstream separation chamber with multiple outlet channels to allow sorting in a "free-flow" format, similar to designs used in free-flow magnetophoresis, 35 electrophoresis, 36,37 isotachophoresis, 38 acoustophoresis, 26 and diamagnetophoresis. 39,40 Since the sorting mechanism leverages the intrinsic differences in density between the ice and water, the separation acts in a passive manner without the need for actively applied external forces and associated apparatus.…”

“…This concept is particularly timely given the recent surge in microfluidic platforms being developed for the droplet-based study of ice nucleation, [43][44][45][46][47][48] including for applications such as cryobiology [49][50][51][52][53] and atmospheric science. 34,[54][55][56][57][58][59][60][61][62]…”