Nanoparticles are increasingly useful in industrial processes, consumer products, and environmental applications, and are also of increasing concern as contaminants of drinking and environmental waters. The goal of this project is to develop deployable methods that enable routine and reliable measurements of nanoparticle contaminants in complex media. This is critical to capitalize on the beneficial properties of nanoparticles such as in filtration and purification systems, to understand and mitigate any unsafe exposure, and to enrich understanding of nanoparticle states in water systems.  We explore microdeposition and correlative microscopy to measure concentration, size, and composition of nanoparticle suspensions. First, we introduce a new capability to measure suspension concentration from dimensional metrology of flying microdroplet volume and single-particle counting with an accompanying comprehensive uncertainty analysis. Then, we study the limits of differentiating nanoparticle size and composition by darkfield optical microscopy by direct comparison with scanning electron microscopy. Finally, we suggest strategies to reduce adsorption of nanoparticles during sample preparation and to account for dependence of optical scattering signal on particle shape and adsorbates. While we are developing our methods using common metal and metal-oxide nanoparticles, they are extensible to organic particles such as microplastics and biological nanomaterials such as exosomes and viruses.

Characterization of nanoparticle suspensions with microdeposition and microscopy

2019 Fall National Meeting

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